BTW, it is probably not hard to get a bit later Cocoa working, at least for 10.5+. For example, here is the history from 2.0.7 release down: https://github.com/libsdl-org/SDL/commits/b89cac6761e9ab48e1b6149a0da90d47baf6f925/src/video/cocoa
There is a breaking commit: https://github.com/libsdl-org/SDL/commit/4a468739f832615dcc21f52e695659e5e93da2cb – but it is small and easy to revert. Otherwise it seems that 10.6 was still supported in 2.0.7 by upstream and fixes for < 10.7 were added (which is what makes it potentially worth bothering with).
Upd. Ah, I think I get what made 2.0.3 a fix-point. This brilliant commit: https://github.com/libsdl-org/SDL/commit/0e45984fa036fff1912c62fee3ed4f5481f3c324
That’s beyond ridiculous.
It probably makes a better sense to look through commit history after 2.0.3 to see if there are some fixes to backport, rather than trying to fix anything later than 2.0.3. The latter will be too much of effort and perhaps not much benefit.