I probably would have done this but I honestly didn't think many people would play the pack due to it being entirely made of custom tilesets
Well... if I were willing to take the time to replace all non-collectible rings in your pack with collectible ones, would this be something you'd be interested in? It can probably be done via RegEx in a few seconds, tbh!
EDIT: I've done it and it's worked. I've sent you the pack via PM in case you don't want to release it with this change.Also, I'm sure that your pack will end up being played by most of us, at least to some extent. A pack of this size and scope and with its Sonic theming is likely to attract anyone who loves Lemmings and Sonic, which I suspect is the majority of the people on the Forums

I focused more on talismans which unfortunately cannot acknowledge collecting all rings
There are ways to do this, actually. The rings could be placed as buttons which unlock a locked exit, and there are a number of ways to make a talisman require accessing a locked exit (placing a neutral lem near the locked exit and requiring n+1 would be one way, for example). Not that I'm suggesting you do this at this late stage, by any means, but it's maybe something to consider if you make any more sonic-themed levels in future.