I am listing my townhome as a shorter (medium)-term fully furnished rental (30+ days required but less than 1 year, not Airbnb) and am planning to appeal to travel nurses, interns, and maybe those who just need some temporary furnished housing for a few months. 

Since it sounds like you will be getting a loan it's going to be even shorter.

I am looking to fund fix and flip deals, so shorter terms basically between 6-12 months. 

But since there is a limit to how much money the bank has access to....their rate will be higher...and usually a shorter term.

To make this "long-winded" story shorter, I bought hundreds of donated vacant parcels that people from "all over the country" that donated "real estate bubble" parcels to Habitat for Humanity.

The medical services in the short term will be affected some but as economy rebounds a lot of elective procedures will have a huge back log and ramp up so doesn't concern me that much.Anytime a tenant asks for rent concessions that can be an opportunity to modify the lease for long term value to the landlord in exchange for a shorter term reduction. 

in what conditions you would prefer shorter loan?

Once you’ve got some longer-term plans, break it down to shorter time periods.

My agent wants to write a shorter timeframe, but my mom who works in escrow is telling me that everything is delayed due to COVID.Thoughts and suggestions? 

Another market to plug into are traveling healthcare workers (nurses, physical therapists, physicians assistants, etc) www.furnishedfinder.com - they rent shorter term than a long term tenants but longer than VRBO & Airbnb.