Very possible, however I'm still not ruling out the fact that corner sticks out beyond the roof covering (& gutter system):
View attachment 275413
View attachment 275414
Now I know you can get localised blockages but it seems a big coincidence that the water lines look almost exactly where it juts out, the waterway appears like it would spill out over a larger area and need to be blown back to hit that terracing wall. It is also very neat lines, if was blocked I'd expect perhaps the inside corner to be dry or at least a lighter colour and the points where it intersects to be darker.
And yes, I am that sad!
We may get a clear video that shows exactly where the water is coming from and it shows I'm totally wrong and it is from the guttering channel, but until I get proof I'm hedging my bets.
It's no biggy whatever, if it's blocked they'll sort it. If it's what I think it could be they'll cover it up from inside as per the designs.