You're correct about the G and J and the X, their expected shapes need to be obvious, the curve of the G and J need to follow the convention of of the C for instance. I have added an extra dot to the arm of the J to give it more presence. Then the X, the intersection of the X strokes needed more attention, looks better now.

As for the é, I don't think that suggestion would work as 4 LED's right beside one another like that will only result in a dot (see fullstop) it wont be clear what letter it is, LED lights cause a lot of light-bleed and that could be problematic.

I've updated a few other letters too, such as ú to make it follow the style of the á.

Thanks for the feedback, it's very helpful.

Before on the left, Update on the right.

A mock-up of how this typeface may look in use.