But I don't see your point on why it is good to call the different parts completely different names. I'm fine with calling things the "Perl compiler", "Perl interpreter" or "Perl VM".

That was fine for Perl 5, where the language was defined by the compiler/interpreter, and there wasn't any chance to ever have a competing compiler/interpreter.

For Perl 6 that's different. The language is defined by a bunch of text documents describing the language, and a test suite that is becoming the code representation of that specification.

There are multiple Perl 6 compilers in the works (namely pugs, Rakudo, Elf, mildew + smop), and calling them all just "Perl 6 compiler" would be very confusing.

If you like the analogy, there's also not "the C compiler", but various of those (GCC, MSVC, Borland, Intel's s C compiler, Sun's C compiler, TCC, ...)

For parrot it's a bit different: its purpose is to serve as a virtual machine for multiple languages (Perl 6, Lua, TCL and Ruby, to name just the most active or advanced compilers targeting parrot), so it wouldn't do the project justices to call it "the Perl VM".

But in the end it'll all be Perl6.

In the end Perl 6 will be Perl 6. Nothing more, and nothing less.