In the music I received it’s written in 9/8, but really should more logically be notated perhaps in 3/4, with each of the 8ths from the 9/8 version becoming an eighth note triplet in the 3/4 version:
Is there some “magical” way to convert the entire score this way in one fell swoop??
There’s no way to do this quickly. Obviously you can use the “tupletify” feature to select each successive rhythmic grouping of three eighths and convert them into triplets, but you’ll have to do them one by one.