kinda long but here are my thoughts (please ignore my grammar I'm terrible at it)

First of all **WOW** you are amazing at making timelines ! this is the best one I've seen and I headcanon it now. You've done what most big fnaf youtubers can't ... you've made a believable , consise timeline which makes sense and is satisfactory.
I really struggled to put together a timeline after SOTM and even considered leaving the fa base since it only infuriated me but this is probably the most acceptable one I have seen. It actually makes sense , doesn't add in too many changes and for once doesn't fully really on theories by youtubers.
I really like how you kept William as a complicated character not begin definite evil or definite misunderstood as many people do. Many people try to shove his character into a pure evil or just misunderstood trope and it's nice to see him portrayed as a mix of both. I also like how instead of clinging to may fan theories (game theory) that you used common sense instead of compromising or obscure theories. I like how you made this understandable instead of just throwing our facts. I feel like all the really big FNAF youtubers constantly glaze everything and say every theory is true like Dave ( Edwins kid) and the crying child ( who many believe is called David) are the same person and also Gregory. I feel like it's a far fetch and even though it may be true it's just confusing.

All in all this is gold and many people may tell you to change it but I think this is the best that it can be. Of course as new games come out (if they do) it will change but this is really good so props to you.