What exactly constitutes the "frequency" of a loop?  :-)  Are you referring to the sample rate/frequency a given loop has been recorded at? What would you need this for in the context of Music Maker's pitch-shifting? The pitch-shifting/resampling/time-stretching feature is offering you the possibility to change the file by tone steps or beats. So, it's rather goal-oriented and doesn't require you to do any calculations of how you need to adjust the playback sampling rate to achieve a certain change in pitch or speed.

If you just want to know the original sampling rate an imported audio file has been recorded at, just right-click on it in Music Maker and bring up the "Object properties". That wouldn't have any relevance to pitch-shifting, of course. And this value wouldn't change through time-processing anyway, since it's a non-destructive effect in Music Maker.

I hope this info helps.