but returning from inside a try block is still a problem (and not fixable as long as try blocks are implemented as sub refs),

returning from a 'try' block is not fixable at all. Because 'try' has to be implemented via eval and return in an eval just leaves the eval, it doesn't return from the enclosing subroutine. So this particular problem is a problem with Perl(5)'s implementation of exceptions and not at all a problem specific to Error.pm.

For the problem with Error.pm, s/try/catch/g on your statement:

but returning from inside a catch block is still a problem (and not fixable as long as catch blocks are implemented as sub refs),

Interesting, I thought that eval would allow a return, but you're right, it doesn't. So there are two problems that prevent this from working intuitively with return statements and neither of them have any known fix in Perl 5.