TBH, I have no idea. I just copied what was there and extended it. I think it’s been like that since the house was built in 1960 so assume it’s okay.
Yes, what was there was fine, but instead of adding a length of timber to the existing ones running lengthways, you should have removed the existing ones and replaced with one long length of timber. The house isn't going to fall down or anything but if you stand on the side of the opening, it will bow in the middle, maybe eventually damaging the ceiling.
In the picture looking down through the hatch from above, the timber on the left looks like it runs full length, which I'd expect, on the right it looks as though it's 2 or 3 pieces which is where the weakness will be.

