I
still haven't read most of the
HOME books, including WJ. However, let's look at the definition of the word "betray":
betray verb
1: to lead astray
2: to deliver to an enemy by treachery
3: to fail or desert especially in time of need
4 a: to reveal unintentionally b: SHOW, INDICATE
From Merriam-Webster's Collegiate Dictionary
According to that, both Maeglin and Húrin "betrayed" Gondolin. My feeling though, and I think the inhabitants of Gondolin would have agreed, is that Maeglin was more culpable in the fall of the city, since
his actions were deliberate, whereas Húrin was simply desperate and careless. Húrin could have easily told Morgoth all about Gondolin during his captivity in Angband, but he withstood years of torment instead.
And the indications are, in the
Silm, that it was Maeglin's going too far afield in defiance of Turgon that allowed him to be captured in the first place. So that was basically
twice that Maeglin betrayed Gondolin, the way I see it.