Catching unescaped pipes
Fragment of a discussion from User talk:Kephir
Yes, {{rfv-failed|<span class=foo>quux</span>xyz|bar}}
would also fail to be caught (it should be noticeable visually, though). I fear some performance problems with that solution, though. Maybe add it to ugly hacks for now.
— Keφr
I added a check_for_extra_args function to Module:ugly hacks (I haven't tested it yet). I don't see why the performance would be bad at all (the slowest part would probably just be loading the module), especially since these archive templates tend not to be transcluded too many times on one page.