To keep it vague, many actors who liked working on Trek and who the show staff liked working with would often come back as either other characters or their popular characters via various means (time travel eps, dreams, etc). Tasha’s actress does make several reappearances and Tasha’s story does get some continuation/wrap-up story wise (to effect the character is not forgotten by the other characters or the writers after she dies), but the actress never rejoins the cast as a full-time regular.
Not sure how it works on Lemmy, but I’d be for this! I’m the same with you with liking to easily find the discussion posts for movies each week. Since this is movies and TV maybe there could be the option for adding posts for new ep discussions for TV shows people want to track.