Here is an update for my Nacra 5.2 riging
I have done some more research on the shrouds and forestay mystery on my Nacra 5.2 and I was able to dig up the old set (very damaged, not usable)

The lenght are:
The old set: Shrouds = 245" forestay = 219.5"
The installed set Shrouds = 240.5" forestay = 222.5"

I am pretty sure that the installed wires are from a Nacra 5.0 and that the old set is for the Nacra 5.2

Right now, I have remove the forestay extension and installed shrouds extensions and the mast is OK but my mast rake is at 18" (With the forestay extension, the mast rake was at 32")

I will try to reduce the mast rake by replacing the front Forestay ajuster or by connecting the forestay directly to the bridle wires.

I still have an old set of shrouds from my Nacra 5.7 so I will probably cut then to make a new set for my 5.2 i am still waiting for a second opinion about the length for the shrouds.

I might also recut an old shroud from the 5.2 to make a new shorter forestay.

I am really thinking about running my boat Unirigged most of the time so I want to have the mast very straight. I might also install a chute later on. (I already have the chute and almost all the hardware).