I define critical mass as: "Enough free cash flow to handle all my financial needs in life, create abundance, AND be able to actively expand my business or invest in new ideas as I see fit."

My tenants seem great, are definitely financially capable, and their previous landlord had great reviews (they rented from her for almost 3 years). 

A simple path to Financial freedom is: Save 50% of your income, use your savings to invest in a multifamily property that cashflows and can allow you to force appreciation by rehabbing it. 

Unfortunately, I have not had the time and the only action I have seen is buying a place at the beach (not a financial investment, wife aspiration).

Since this isn't a financial gain for them (they already have the sale completed, so to speak), it's just paper pushing and not worth their time.

In April 2018, I read Rich Dad Poor Dad after running the numbers and realizing we would never reach financial independence with our current rate of active income.

He could delay important repairs and not do them to make the financial statements look better. 

In terms of keeping both parties legally protected financially and legally?

Definitely want the building enough to do what it takes, just sometimes doing what it takes is not what makes the most sense financially and logically.

The "right" answer for you can certainly differ depending on the whole picture of your financial, tax & business activities.