Is there a simple way to figure out if timing belt service was ever performed? I see that the engine side cover bolts were unscrewed at some point (there are signs on them), which might indicate that the service's been done previously. Are there any other ways to confirm that?
Unfortunately there is nothing in carfax report about timing belt, some records do not provide details. 2017 Acura RDX with 130000mil

 

You can take off the timing covers and examine the belt, but the best way if you're not sure is to just go and do it all over. Check the timing belt tensioner to see if it looks clean /new. That's typically a good sign as well.

 

The old original belt will be shiny and possibly cracked, the old tensioner will be covered in oil or heavy corroded.
Also, a cold start with a weak tensioner may be accompanied by a crackling sound for the first 10-15 seconds, depending on the amount of oil remaining in the tensioner.