Kris, I'd be happy to suggest better settings for your dad's comfort. The current settings and the answers to the following questions would help:
What is uncomfortable? Pick all that apply
Breaths too long/short/switch from inhale to exhale too soon/late/switch from exhale to inhale too soon/late
When he breathes in, he feels like air flow is too much/little
When he breathes out, he feels like air flow is hard to blow against/that there is not enough to keep the airway open
It would also help to know more about the tests. "PFTs" is a general term and we don't know which test was 20%. Your mom should be able to get a copy of the results from clinic, and you can post them here. But if the 20% refers to FVC or SVC, that does not mean he is weeks or months from the end, necessarily. He could well have a year or more. There are other factors, like how well-nourished he is.
I would also ask for regular oximeter readings by the hospice staff if you don't have your own (they are sold in drug stores), and those readings might also help answer your question. Also, you say that they don't tell you much. You have a right to know everything they do. Take it a level up if your staff is not cooperative. Explain your concerns. They are people, like you.
For all, it's always a good idea to take home or at worst have mailed/e-mailed your clinic notes and all test results, as with all the docs you see for anything.
Best,
Laurie