The Y axis rods start with a 52.5 cm space and end with a 51 cm space, which blocks the movement along the Y axis... I don't see where I mistook because I couldn't have misplaced something thanks to the keyed parts... Please help me
52.5 cm minus 51.00 cm = 1.5 cm = 15 mm = big = 5/8" ish. There is no way that the frame would fit together if the smooth rods had a difference in distance between them of 15 mm 5/8" in old money. I have just measured the (inside) distance between my Y smooth rods and it is roughly 50.2 cm Check the distance between the rods themselves furthest front and furthest back, and also run through the commissioning again. or just slack off everything holding the Y rods and move the X-Carriage back and forth.
The frame fits alright, I'm afraid its the position of the drillings that don't fit with one another : They are spaced 52,3 cm at the front and 50,8 cm at the back, and the rods holes seem quite aligned with the holding holes on the Y-Axis Rear Brackets ....
The overall width in front (your second picture) is 53.9, the distance between front mounting holes is 50.2 on my printer. Maybe your X rods are not inserted deep enough.
You will need to carefully run an 8mm drill into the holes to allow the rods to push in all the way and have some freedom to move while you commission the machine.
An old trick if you have not drilled the holes out already is to turn the drill bit anti-clockwise to ream the holes out.