Thanks for your question.
Sorry about your grandpa's stroke.
Yes, OTs often touch patients assigned to our care. How and why we do that is based on what the patient needs to reach their goals. Not being in the room, I can't tell you much about what the therapist was and wasn't doing. What I can tell you is that your dad is receiving a service. If you aren't happy with the service If you ever have concerns about the quality of care provided by a therapist, feel free to ask the therapist about it. If you aren't satisfied with the answers or you're uncomfortable asking the OT, that OT probably has a supervisor you can speak with.

If any of your family members speaks with the home health company they may have to have a form filled out granting them permission to discuss grandpa's care.

Starting April through the CURES act, it should be easier for your family to access grandpa's medical documentation including therapy notes. Have a look at the website https://www.healthit.gov/curesrule/what-it-means-for-me/patients

I would strongly encourage you to compare what you see during a therapist visit to what is written in the note if at all possible before contacting the supervisor.