This is one case where we really should support the original product, you can buy a perpetual licence of a pittance and they just 2 guys chugging along.
LibreSprite has 5000 commits, 30 in the past year whilst ASEPrite has over 10000 at this point.
Libresprite is an important project because people can fork it and learn from it by extending it, and submit those patches upstream, regardless of how active it is.
A fork of the old version to have a slightly better version conveniently available in package repos would be nice. I don't think it has to catch up with Aseprite to be useful.
It's good to support honest and high quality proprietary software.
Aseprite offers the latter good, this offers the former good.