They claim that since there had never been ant enforcement of the restrictions, there's no reason anyone should have found it.You need a new attorney.

I also see a neighbor got code enforcement investigation from city inspector and applied a sfh- historic administrative to rectify their windows.Can applying for a single-family permit offer a workaround from historic planning for window replacement?

No growth, job security, new infrastructure, poor school systems, lack of policy enforcement, etc.

If the ground rent isn't registered, the annual rent, etc. cannot be collected or enforced and there's no point even worrying about it.If the ground rent is registered, you can determine the exact amount to redeem it -- it's a simple calculation based upon the date of the original lease and the annual rent.

I feel like with impending legislation, especially in NJ, it is becoming more and more difficult to be a private landlord    

It is a great strategy to throw into the mix when you are working with a lot of reserves, but if you assume a loan at a 3% rate and rates are in the 6-8%s now, then it is a no-brainer for banks to enforce the "due-on-sale" clause and call the loan due on a transfer of title so they can use those funds to make mortgages at the current market rates.

Not to mention the upcoming legislation on the November ballot that can really hinder your returns from renters.

The amount of bonus depreciation you can take may change each year - 2023 the amount is 80% (but there is legislation that may change this to 100%).Actively managing the property doesn't change the IRS rules on whether or not an asset is eligible for bonus depreciation.

This is a bummer because if its at the city level than it would mean both properties under HOAs and ones not under HOAs would be affected if they truly enforce this.

Also research Rent legislation,  many states and towns are looking at rent control.