Tenebrae

This may have made sense back when the show only had 2 seasons. However thanks to the Cutie-Re Mark episode Faust's explanation doesn't make any sense in the context of the show. So we either take this statement as an outdated explanation of a certain event in show made by an individual who hasn't had any input on the show since season 2, or we accept it and turn Celestia into an even more incompetent ruler.

When characters can dodge lightning but are generally portrayed as slower and the like is when it becomes clear that there are certain inconsistencies that aren't meant to be taken too seriously due to the nature of the show itself. When do Unicorns shoot beams of light? They shoot beams of magic which don't move anywhere close to the speed of light. Your ignoring external context. Like Simcity11100 said the animators probably just used those visuals in order to make the scene look cool without really knowing the physics of what they are representing (a common error among writers/animators). The reason I believe Rainbow doesn't go much further than Mach 1 is that its pretty clear her Sonic Rainboom is supposed to be the equivalent of a Sonic Boom. The name is basically the same as and the sound used for it is basically the same. You say that we have to go off based on what we know and see and that is exactly what I am doing, but I always try to maintain the perspective that the animators/writers are not infalliable and that it is very possible (and common) for them to fail to represent what they truly meant to portray due to a lack of knowledge in science. That being said it is clear that those like you and those like me just view this too differently to come to an understanding. So unless the showrunners decide to explain themselves we will never consensus on this topic.

Only some of it was canonized and even then there are some minor differences. It doesn't change the fact that a large part of it was retconned and as such it is no longer credible source of information. That said it doesn't mean everything in the Journal is wrong, as Season 8 shows, however it no longer can be considered primary canon due to Season 7. Season 6 makes it very clear that Alicorns are not meant to be born as they have to earn their ascension which is why everyone was so shocked by Flurry Heart.

Nowhere. It is never explicitly stated that Celestia and Luna are artificial Alicorns. However S6E1 heavily implies that all Alicorns prior to Flurry Heart had to earn their ascension, which is why her birth caused such a commotion. The book "Journal of the Two Sisters" had stated that the two were born Alicorns however the canonicity of this book has been put into question since S7E25 changed everything the journal established regarding the Tree of Harmony and Starswirl to some extent. So essentially the people who believe the Journal is no longer canon believe Celestia and Luna to be artificial while those who believe the Journal to be canon believe that the sisters are natural.

That's precisely why I am confused. Gallus never really seemed the leader type. The problem is that none of them fit the Element of Magic, so my guess is the developers will come up with some reasoning as to why this is if they decide on going down this path.

It would be nice if there was a better reason other than because all the other spots are taken.

How could Gallus possibly be the element of Magic?

There is no canon answer to that questions thus far, however the most plausible theory is that Celestia and Luna are connected to the Sun and Moon and that as long as both celestial objects exist so too will the sisters. However people are still divided over whether or not the sisters are born Alicorns. If one was to only use the show as canon, season 6 heavily insinuates that all current Alicorns (except Flurry Heart) earned their ascension, which is why Flurry's birth caused such a commotion. It was previously established in the Journal of Two Sisters that Celestia and Luna were natural Alicorns, however some don't see this source as canon any longer as season 7 chose to retcon a large section of that book.

That's more of an assumption than anything. Its so easy to say, and almost impossible to prove. Of course factors are important, but so is the amount of power one wields. Cadance has only aged until adulthood, as have Celestia and Luna. So for all we know Cadance will also life for a long time.

It still sucks to return 1000 years later and everything and everyone you knew is gone or has changed. But perhaps I am projecting too much realism into what essentially is a TV show for little girls. The problem with power levels in MLP is that we are never given an accurate measurement on how powerful one individual is compared to another. All we know is that there some or stronger than others but never by how much. So far we know: Discord > Celestia + Luna Starswirl > Alicorn Twilight Celestia + Luna > Sombra Pony Of Shadows > Alicorn Twilight Pony Of Shadows > Starswirl Amped Chrysaliss > Celestia Chrysaliss < Alicorn Twilight Nightmare Moon < Daybreaker Alicorn Twilight >= Starlight Nightmare Moon > Celestia (presumably)

I'll agree that since we are never told her intent, assuming anything can be fallacious. Actually I know very few magical systems that hold that you are born with your full power. Regardless you cannot use this to assume the way magic works in MLP, that would be a huge assumption. I rewatched the scene and the magic surrounding Twilight doesn't look like a shield at all, and Celestia's hoof moves in with no resistance or "break" in the shield. It seems we just see things differently, I guess.

We don't know what she intended. Banishing your sister for 1000 thousand years seems needlessly cruel and our of character for Celestia so I doubt so really meant for the elements to do that. I also doubt that the elements do whatever the user wishes as I don't think the elements could ever be used to commit a terrible act. Also the Mane Six were probably not trying to purify Nightmare Moon since they had no idea she was Luna, to them Nightmare was just evil. Yes I am pretty damn sure Unicorn Twilight is weaker than Celestia, especially when she was just a foal magic outburst or not. I maintain that Twilight did not have a shield, and anyways Celestia's horn didn't glow so she was not using magic, all she did was put her hoof on Twilight's shoulder without any resistance.

A tool does not equal personal power. Especially one as powerful as the elements of harmony that are magic McGuffins. Celestia may have been able to use them solo but she was unable to use them effectively as they only banished Nightmare Moon instead of purifying her and even that was only temporary. Wielding the Elements only means that they find you worthy of it not that you are yourself very powerful, and at any rate Celestia and Luna were not able to use the full power of the Elements as they only manifested their true forms with the Current element bearers. Magical shielding? Wut? Glowy magic =/= shielding. Of course you have not seen it done elsewhere since its the only instance it happens. You are assuming far too much. Unicorn Twilight is weaker than Celestia so I would expect her to be able to deal with her spell. Discord may be powerful but even he has limits.

Fair enough on the Canon part. Celestia did not shut her down with magic, she only calmed her down. Celestia only defeated those two with the Elements of Harmony so that is not a personal feat.

The Journal has been contradicted multiple times, namely the whole part of Starswirl and the Tree of Harmony has been completely changed. That to me is enough to no longer consider it canon. Comics are secondary canon at best and they are often contradicted or they exaggerate things or make characters act differently then they do in the show, that's why I only use the show + films when discussing topics. Comics should only be used to re-enforce a point already made in the show. When has she sut down Twilight? I don't remember that in the show. Celestia defeated Sombra with the aid of her sister, so she didn't do it alone. Its never stated how Tirek was defeated the first time. She never defeats Nightmare Moon or Discord. So no, she doesn't really have a good tract record. Yes Daybreaker is her full power, but she access that full power nilly willy, nor would she want to as it turns her insane.