I'm also not sure what you mean by foreign national lenders. The U.S., unlike many other countries, doesn't restrict ownership of land by non-citizens. Lenders generally don't care where buyers are from, as long as they have sufficient funds. Foreign currency denominated accounts are fine for proof of assets (I have a client in Japan doing that, and recently had one from Bermuda). They may want proof of income (e.g., a job offer letter from the city they're buying in), but otherwise being foreign shouldn't be a problem, unless they want a mortgage and don't have credit for some reason (credit isn't as popular in other countries as in the U.S.)
In my experience this nearly always works out, although there are issues with documentation (e.g., foreign tax returns). I guess it depends "how" foreign they are; if all their documents are in Urdu that might be a problem :-) Generally just choose a *big* lender, and ask for a processor experienced with foreign transactions. I'm with Coldwell Banker, which is international, and I've closed deals with clients in New Zealand, Bermuda, and Japan with no insurmountable problems.