Looking for bookkeeping firm knowledgible about HOA

Ask a few CPAs, other HOA office people, and even a Developer. Also, even landscapers and painting and roofer crews will have been hired by other HOA, and they will help you know who they found easy to work with and who was not a good manager.

I don't know about the HOA rules in your area, but there are large service providers that do only that task. Your fees might be prohibitive with only 22 units.

I recently gave over the contract for a county water district, and there were lots of similar districts with bookkeepers, as well as small towns whose financial managers were listed with the State. Have you asked your City or County Clerk who they work with when these HOA need liens filed or other legal matters handled?

Insurance providers likely have bonded some of these individuals or firms that do this scale of work.

And have you let all the owners know you are looking? I handed off that water district contract to one of the owners in the district.