You are describing the debugger API via M-x perldb.

It runs the debugger in a terminal emulation in an extra buffer and is in parallel scrolling the current point in the original source buffer.

And it kind of works after typing c for continue (debugger command) I can input stuff. It actually looks exactly like when run with perl -d

Tho it doesn't seem to have auto linking of Perl's error messages.

I will update my OP later with an SSCCE explaining the output.

> I was under the impression that it launches programs under debug by redirecting its STDIN and STDOUT to a "console" buffer

Well I'm using mode-compile but emacs is more TIMTOWTDI than Perl. I think mode-compile was originally designed for make that's why interactive input isn't that important.