Construction next door - damage

I live in a two family 1900 Brownstone. The next door building was bought by a developer. He tore the whole building down, dug out the coal room underneath the building, changed the floor placements, added a huge extension to the back, roof deck with an added structure, ripped the original brownstone off the front- everything! The front door is now street level. Huge job – it has been completed and we now have new neighbors.

Our neighbors have had some moisture issues on their walls (shared wall with us). So far it has been friendly, but clearly the developer has told them it is probably our old house causing the issues.

We have not seen water damage like they have but have seen cracks and some bubbling right below where they have their damage.

We have had two inspectors that have said it is not our fault but probably due to the construction. The neighbors keep contacting us as though it is our issue. We just want this to be over – I can’t help but feel like I let this developer off easy but here we are. When we had our home inspected the inspector noted that he had concerns that the firewall was not properly adhered and could lead to moisture intrusion. The developer also did a poor job with sealing our shared wall with the roof structure. Used rubber sheets for the neighbor on the other side (who was also the broker) and on our side we got tar paper and glue.

My question here – with too many issues to name – how can I deal with the neighbors about the moisture problem? Our home was fine before construction – all these issues have only come about after the huge construction job next door. Do I get a lawyer? Should I have an engineer come in to check my house? This seems like it will never stop! Thanks in advance.