This might be over-engineering at this point, but it was my not-so-secret
hope when suggesting along this line that there would be a good place to
add a branch in the middle, where the system would offer more than one
(incompatible, at least sometimes) choice to the user, with the hope of
eventually being a bridge to "hey, this looks like C-Sharp. Would you like
c-sharp-ts-mode or CC-mode for this? (Now/future/ask again later)" and
maybe also "This is probably Perl or Prolog code. Would you like perl-mode,
cperl-mode, perl-ts-mode, prolog-mode, or...."

I hope this helps,
~Chad