Can I build a smart playlist populated by songs I’ve loved within the last x weeks? I have a smart playlist that basically features the songs I’ve “loved” (❤️) within the last two weeks. To make this playlist work it would mean that I’d need to know when that song was “loved”.

Is this even tracked by iTunes? If not, is there a workaround?

Thank you!
The workaround I use is the use the "Grouping" info for each track (in addition to or instead of the rating).  That won't help you if you use Grouping for something else already, but updating the "grouping" will change the "modified date" for the track, which could then be used as a criterion for a smart playlist.