First, thank you for this detail.
Second, S8 is basically one school year at a much less frequent rate of episodes (instead of 30-50 episodes in a year, it's about 25).
This timeline gives us about 4 years for the full series so far, and does so nicely, only at the expense of a significantly higher rate of episode shuffling / season border crossing. It might help a bit if you make the year separations significantly more clear.
What I see: Year 1 is seasons 1-3. Year 2 is seasons 4-5. The end of 5/start of 6 is a little muddled ("little"? ha).
Season 6/7 is a little more than year 3, also a bit of year 4 (basically all of the summer vacation), leaving season 8 starting at the start of the school year 4.
I like this.
If the CMC's have the "late birthday curse", they would be 7 going on 8 at the start of the series, and then 11 going on 12 at the end of 8. These would be like children whose birthday is just after the deadline, who feel like they are a year behind other children in school.
Yea. End of season 8, 11 going on 12, wanting to study more advanced magic ...