I need some guidance with this one before I just reach out to a lawyer.

I'm not a lawyer, and you can speak to an attorney about this, but in my experience people are typically thinking that putting their property in an LLC "protects" them. 

We are getting push back from the seller about creating a purchase agreement with our lawyer that they would then need to review with a lawyer.

If the landlord was aware of his past, yet rented to him anyway - any lawyer worth their salt would make a nexus between those two pieces of information and create a liability claim.In addition to the extreme negative press you would get, it also takes time, money and energy to defend a lawsuit you will eventually win.

I used several lease templates that I found as a starting point, then created custom leases for my properties from those, and had my lawyer review them.

I would consult a lawyer and listen to his advice but where I would try to direct this is the lawyer write letter to HOA that they do not agree with the HOA interpretation that the current CC&R does not allow STRs.  

Are you dealing with a real estate lawyer?

In addition if you use a title company or lawyer to handle the closing then they are legally required to report the sale to the IRS etc.

Request advice from anyone who is either a lawyer in Ohio or is knowledgeable and experienced with Ohio rental laws.

I have spoken to many lawyers.