Correcting an imported score where tuplets were not recognized

I'm a newbie, and did the best I could to search for existing answers in the forum, but all I found was a post from 2011 that seemed like a similar issue, so apologies if this is a duplicate question.

I've imported a Glière piece via pdf scan, intending to simplify the cello part so I'm not incapable of playing it :)

Anyway: The piece is in 3/4 time, and much of it consists of eighth-note triplets. In fact, every single eighth note and eighth rest in the entire piece is part of a triplet. However, the scanner decided they were all standard eighth notes, which appears to have resulted in the whole thing being interpreted as 9/8 time, filling in rests as needed. Screen capture attached.

Is there a reasonably non-labor-intensive way to fix this? Thanks!