Yes it's a huge problem.You should fix this correctly now.Open the walls and put in proper sound reducing insulation.

As far as I know, your assumptions about the tax implications are correct for non residents, it was one of the main factors that stopped the idea of investing in Spain for me.

@Jerry Chilimidos,Ned is correct, if you end up refinancing your rentals in the IRA - your IRA will be subject to UBIT tax on leveraged portion of the income so be sure to run the numbers with you CPA to understand the tax implications. 

You are correct by saying that you have missed opportunities by being too cautious.

🎯 The Real Parallel for Real Estate Investors:AMEX and Coca-Cola together show Buffett's core principles that align perfectly with real estate investing:Buy Quality Assets During OpportunitiesAMEX during the crisisCoca-Cola during market pessimismJust like buying good properties during market corrections!

My recollection is (and insurance experts on BP can correct me if my memory is wrong), but most insurers will only pay "replacement cost"  policy limits, if you actually replace the damaged property.

At the completion of your due diligence, you have 3 choices; accept the property as-is and move to step 4, reject the property and walk away, or ask the Seller to correct any items that you request. 

Also make sure you protect yourself with the correct contract documents. https://www.myfloridalicense.com/wl11.asp

@Charles Perkins is absolutely correct about "collecting all receipts, properly tracking all income and expenses and your basis for all assets properly documented and recorded."

Small correction.. by small apartments we would be looking at 20-30 doors.