Ultimately, I do think S8 requires scale and lots of efficiencies but has its benefits. 

I'm trying to give them the benefit of doubt that he just DIDN'T know.

This approach allows you to have a legal presence in the country, which is often necessary for investing there if you don’t live in Spain.Having a virtual office in Spain through your LLC could help you access local tax benefits and deductions, such as expenses for mortgage interest, repairs, and insurance, which non-residents typically cannot claim.It’s worth consulting with a tax or legal advisor familiar with both the US and Spanish systems to ensure compliance and take full advantage of this option.

It will familiarize you with the basic terminology and benefits.

My strategy is to hold it long-term, leveraging the steady rental income while benefiting from potential appreciation.

Aside from basic maintenance which is simple work, but hard and monotonous work, and keeping the asset positioned to fulfill it's highest and best use, there's nothing you have to do past a certain point to benefit from market appreciation.

I think there is value in ADU as long as it is legally done and can be legally rented.On the sale side a benefit can always be an in law suite.

You are (older/retired) and could benefit from house hacking and buying a duplex, or renting a room.

Would either of you be willing to explain cost segregation and benefits of using it as an agent?

Being able to shuffle leads from MTR to MTR is a huge bonus and you can benefit from the economies of scale faster.