Although there has been some success with the immigrant community.

For taxes and immigration/foreign investments, you'd definitely have to talk to a CPA and/or an attorney.

That’s why immigrants are coming here.

Higher rates matter...a lot.Whether we like it or not, higher prices (inflation) are the consequence of our decisions around things like drilling, tariffs, immigration, and war (yes, we are at war). 

However im suspecting most of the tenants in this area are undocumented immigrants as he says they all pay cash.

He kicked the super out, moved into the unit himself, then rented units out to un-documented immigrants increasing the rents beyond what's allowed, and replaced about half of the tenants that way.

Additionally, single family properties continue to stay hot in NH as the state has been the highest immigrated state in the NE (due to numerous reasons that I won’t have time to discuss here).

I know of investors who have done this using the "whole block" strategy, and I have a reasonable feel for it in my own little area, but outside of that my experience of what makes a neighborhood 'come back':No intrinsic reason for decline other than decline - i.e. it's not next door to a sewage plant or trash dumpHouses were reasonably well-built and well-sized to begin with Within easy walking distance of anything worth getting to - a downtown, a really nice park, a fantastic library, a great shopping centerA high ratio of owner-occupied to rental property(Sad but true) A low percentage of immigrants and minority groups (this could include whites depending on the area); there are still a lot of prejudiced buyers/renters out thereA perception of physical & personal safetyReasonably close to centers of employment

This has been a bigger issue with the immigrant population being issued numbers.I have had to request that the applicant send me a copy of their card and then make a judgement call on whether the card is legitimate or not.

I recently immigrated to the US from Australia after marrying a US citizen who has lived in this area for 2 yrs.