I dunno lol
Yes you are correct regarding the reasons for this change. Ever since the Brave Witches anime had aired, the series slowly become more known as "World Witches" in much of official Japanese media.
I do not recall when exactly the wiki name change took place, off the top of my head. But I believe it may have occurred about... 2 or more years ago? As for the front page specifically; major changes to it were implemented only a few months ago, due to being extremely old. The logo has not changed simply because no one has bothered to create a new one, lol
I hope this helps answer your questions!
Sadly, I must admit that I sorta miss how the old one looked in retrospect. Originally, it only really needed just a few tweaks and updates that's all.
The new front page layout is fine too but it still needs a lot of work, as stated above, and I also agree that the current state of the images makes it look a bit messy, and that protagonists aren't really too important to have cluttering the front page. Tbh I thought I was the only one thinking this, otherwise I would have mentioned it earlier lol... But in the end its all up to you though, and felt I should just mention my thoughts on this too.
I should mention, in case it wasn't noticed, that it still says "VTuber Wiki" in white text on the front page. There is also still some funkiness going on within the bottom of the page as well.
Yeah, goodluck with that! I know it can be a pain messing with that stuff, so even if you can't do it that's still fine.
I think this would be a fantastic idea regarding the character list, especially being able to have a sortable table.
As for the front page, it would definitely be nice to have that finally be updated after all this time! Although if possible.. imo it would be nice to keep the Agahari character portrait links as they were, simply for tradition's sake, although I would understand wanting to replace it if you wanted to stick with official artwork.
Either way, I look forward to seeing how these layout updates turn out later on!