If anyone familiar with lending law could offer some guidance, I’d greatly appreciate it.Thank you,Mergim

Another caveat: there are a lot of STRs out there that are breaking HOA/local government/state/federal laws or strongly bending the rules, and I'm looking for people who did not do that or who mitigated risk there. 

You'll need a portfolio that's $100,000,000 with no leverage.There is less than 10,000 Americans with a net worth that high.

After I resolved that claim the law  Seveney: @Peter WaltherIt’s gotten quirky - like in GA if they don’t pay for so many years then it’s wiped (had that happen but thankfully we got them to mod and reinstate the SOL).  

I don't think it is new, the law passed in 2019. 

Depends how professional the current PMC will be about the transistion.First, have client get all leases.Then rent ledgers.Make sure you get a copy of their current management contract, so you understand the Termination requirements - you don't want to break any state agency laws and have the curent PMC file anything against you.Make sure the client follows the Termination requirements BEFORE you take over.Suggest the owner emails their Termination notice to current PMC and copies you on the email.

After hearing what my relative did, there's another chapter to the story, trading cash flow for appreciation, acquire more properties, due to limitations of the recent tax laws.

To me it doesn't make sense but when it comes to codes and locally specific laws, there are lots that surprise me.  

Can anyone recommend a CPA who is well versed in Real Estate tax law in Massachusetts?

Tax laws are constantly evolving, and staying up-to-date is crucial for businesses and individuals alike.