with regards to your point about retrospectively applying something after an event (ie in this case an LFO when you are taking the developer to court) I had a situation similar (of sorts.)
About 3 years ago I rented out my apartment to tenants. They paid for one month and one month deposit then didn’t pay anything. I got 3 months of story after story telling me how they would pay next week. In the end I took them to court at a cost of €1,000, for non payment of rent
One day before the due date they paid in full. The judge basically said that as they had already paid there was no case to answer. in my opinion it doesnt matter that they had paid it was the fact that I had to take them to court in order for them to pay.
Not quite the same as an LFO but the principle is the same