I should be able to leave notes against each exercise or plan so my trainer can read them

If the trainer plans out a regular set of exercises within a plan, the notes a user leaves should remain on recurring exercise sets within that plan.

And to be able to see your notes if needed the next time you do that exercise, to see if you need to make any adjustments

U already have a notes option for each workout but it would be nice if u had a small notes option / comment option next to each exercise as well . For examplE :
Shoulder press : weight went up but slight pressure on spine .
Squat : good set but last set used a belt .
These things we forget at the end of the workout .

There is a note section to make comments, but they need to fix it so the comments stay and you can go back and read the comments or update them.

If you add a note to a workout, you should carry it over to the next workout so if you have made recommendations for an exercise, you can see them.

Yes! Perhaps also include a box for "perceived effort (from 1-10, with 10 being unable to complete prescribed exercise). Very helpful for tracking fatigue across sets and knowing when an exercise is becoming too easy.

Add a note for the exercises such as "used Dumbbells instead of KB because...." Or "all squat racks taken, did hack squat instead" so I can remember and my trainer can see why the weight was different or what issues I am having etc.

I agree! Things also like 12 push-ups was really 8 regular and 4 from knees so you could improve next workout.

For times when you can't finish a set at a weight n you need to go back, or when the weight is too light and you want to increase weight for last few reps.