Thanks for the detailed response! And it's not that long of an answer, I'm used to being way more verbose than that :p
1) Yeah, I have a "Status report" macro in the bar which prints everyone's AC/HP/PP and I was thinking of having the extension fetch and show all that information from the dndbeyond character sheet and display it right in the "Campaign" page on dndbeyond. That however would only work if all of my players decide to switch over to D&D Beyond and for now, only 2 (out of 7) have tried it as far as I know, and I just told the others about D&D Beyond yesterday.
2) and 3) and 4) D&D Beyond (with Beyond20) is really meant to only replace the character sheet for the players so when you tell them "roll stealth" they can do it from their D&D Beyond character sheet. The equipment, spell management and all of that would just make it much easier for them to manage their character and they can look at an item in inventory and click the button to print out its detail as they say "I will use this". For more specific game management, complex macros, tokens and jukebox and all that, you would still be doing all of that in roll20. Actually as a DM, I wouldn't be using this extension myself because I don't roll for characters (I might actually add support for monster stats and use it to roll for enemies in an encounter but I don't see the point, the NPC sheet in roll20 is adequate and I wouldn't need to be looking at equipment or special feats as much, though it might be easier to see spell descriptions if I play a spellcaster enemy.. either way, Beyond20 doesn't support rolling from monster stat pages yet). As for changing windows, I don't know how you manage your game but in my case, I already open my notes as separate windows and everyone's character sheets and I end up with 12 chrome windows in my taskbar then I split screen (ultrawide screen where the 40% on the right is the notes/character sheets/etc.. and the 60% of the left is the VTT). Actually being able to have one window for all the character sheets (each on their own tabs) sounds better, then I could just switch to it and select the tab directly instead of having to look for the right character in the middle of 12 windows in the taskbar.
5) I'm providing support! :p But yes, I see what you mean. If d&d beyond change their layout, even a little, it might break the extension and while I plan on maintaining it, you can never know. You should still be able to get support from roll20 for things that don't work out if the issue is from roll20 since you can just press the up arrow to see the command/macro that Beyond20 sent to roll20 (just like you can after you click on a roll from a roll20 character sheet itself).
I would say the biggest issue I see now with Beyond20 from my point of view is that we depend on information being accurate from D&D Beyond. For example, in my game, my Life Domain cleric has all her spells show how much healing + how much extra healing they get from Disciple of Life. With D&D Beyond, the Disciple of Life is a Class Feature, and the extra healing from it doesn't show it in the spell descriptions in the sidebar. Casting Toll the dead asks if the target is at full HP or not to decide if it should deal 1d8 or 1d12 damage, in D&D Beyond it just shows it as "1d8" (I told my player that in that case, they can just click on the '1d12' formula in the description and it will roll it, but still, would be nice to have it integrated). If I click on a dagger from the Action panel, it doesn't give me the "To Hit" value, so I have the extension find it from the main page, but if you switch to the Equipment panel, that information isn't there, so your dagger attack only prints damage, no attack roll. If you cast Elemental Bane, the extension picks up all the damages so it will print 10d6 (or however much it was) for acid, cold, fire, thunder, necrotic, etc.. where the spell actually says "choose one damage type", etc...
I will need, in the future to basically go through the entire list of spells and do a case by case check and adapt the code to send out the right information, might need to start having macros/popups in the d&d beyond side (like for Toll the Dead, to check if target sustained damage) but those are basically rare/extreme cases in my opinion and not a big issue for players (click on the dice formula in description instead of clicking on "Cast on roll20" button, ignore all the extra damage and use the first 10d6 rolled and choose the damage type verbally to your DM, etc..), either way, it's still easier than the person already using D&D Beyond and rolling their dice manually.
I know you aren't criticizing, I hadn't seen it that way at all, but thanks for saying it nonetheless :) Beyond20 from a DM perspective or an advanced usage perspective isn't going to be that useful to you to be honest, I wrote it mostly for my players who are too often lost in their character sheets and keep forgetting what needs to be done when leveling up, etc... If it's easier for them to manage their character, it's going to be easier for me to DM.
As for the EULA, I don't see the problem either, sure I can buy material on D&D Beyond and use it on roll20 without paying twice, but I could also have the PHB hardcover and besides, I buy modules on roll20 because all of the maps/tokens/etc.. are all setup for me, that's what I pay for, and D&D Beyond doesn't have that.