[Radek]

I don't think the winglatch is broken. If you will be enough fast with emerging from the water and reaching Goshin, you will see that Goshin is opening a grate in front of itself.
My theory is that the winglatch opens the grate but that it is "one way" - it only opens it and then it stops working. Let us note that all grates in the game have their locks, levers, triggers, or some related tricks (Valeia Crypt). They never act "directly" like doors.
Well, I was unable to check the theory: it would mean Vanishing from the 'X' corridors through the "upper grate" to the Goshin's area and seeing what's the matter with the winglatch before Goshin starts acting but - the vanishing seems to be unpossible.
The wall. I haven't found anything there.