The point is that, in cases where we can identify harmful situations (regarding the optimizer hint), it will be quite easy to fix them now that we have done the refactoring of join order. As I said, I'm pretty optimistic my recent fix will do the job, the problem was that FILTER (NOT) EXISTS was decomposed into a FILTER + subquery instead of subquery + FILTER - and when reordering is disabled this gives the wrong result.
Apart from the FILTER (NOT) EXISTS the only thing I could think of are complex filters that cannot be attached, BIND shouldn't be a problem (please let me know if you observed otherwise). I'll test that tomorrow.
Regarding your second query: I agree, there's a high chance that this has been fixed. If you can provide a reproducible setting please let me know and I'll test it.