From what I understand, those are fine if you're going up against enemies that don't have stealth (and all the ancillary technologies that go with it).
The general military analysis is that the F-35 and J-35 are superior to anything else in the air and are similar in capabilities to each other. Conflicts between them will come down to who can make more of them faster. Conflicts between one of them and an older generation fighter seems to be, they'll blow you up before you can see them.
EU better get cracking and start making stealth planes.
Fighter planes are very expensive to develop.
The F-35 program cost something around $1.7 trillion. ~~That's several times the annual GDP of Canada.~~ That's more than half of Canada's annual GDP.
A better bet would be to enter some joint development program with partners in the EU.