My "barely used" TT had a similar leak. Turns out the previous owner clipped a tree and damaged the seal between the front panel and the roof.
The initial "repair" was done by the mobile RV tech who had been paid to inspect the trailer. He added some screws and applied lap sealant.
When the problem didn't go away entirely, I used a lot more lap sealant across that whole strip connecting the front panel to the roof. We'll see if it stays dry all camping season.
I have permanent cosmetic damage from the first leak. The second leak created a bubble of water behind the wallpaper in the overhead cabinet. I cut that open to get it to dry quickly and completely. Since I live in a very dry climate I'm not worried about permanent damage having taken place.