After ten days, the crossword was finally solved with a team-up of blk2860, Clancy12, and MattEmAngel.
MattEmAngel: I've almost solved the crossword. So far, the letters, top to bottom, are I_R__TTEE_NUHTED_.
blk2860: 27 is Oui, 26 is kgs. Making 33 GUI which sounds like Gooey, and is also a computer term, hence the hint. 54 is Nyet.
Clancy12: 1 across is puzzling and I think, 4 down is zeolites. Also 50 down is ingot. That just leaves 2 blank yellow spots.
blk2860: 63 is anecdotist, and 59 is MIB.
MattEmAngel: 65. is tea table, which confirms 60, ESL = English as a Second Language, and 61, Joan of Arc was a saint, abbreviated to ste. Also 39 is Chordata. 42 is I guess a vocal of the clue. That's what a laugh sounds like apparently. 24 and 35 are definitely not right.
Clancy12: What do you see wrong with 24 and 35? When I was working on the crossword I got "adnexa" for 29 instead of "addons". I didn't think much of it until now but that allows for 42 to be "hehe" and 50 across to be "IRAs", both of which work with Chordata.
The few remaining squares eluded them until a white hot bolt of inspiration kicked them in the head.
MattEmAngel: Which child are you of...? Which child are you of GODS? That doesn't sound right. Which child are you of.... ... It's GAIA! That was from one of Gantic's "Who Are You My Dinosaur"!
♫Are you Hadro? Are you Maia?
Which child are you of Gaia?♫
Of course, well-timed observations didn't hurt either.
silver199: Am I the only one who noticed: GANTIC ... Imprisons Other Mods on Iron Moon
MattEmAngel: *facepalm* IRON MOON!! Of course. "Moon material" is iron. 20 is ELDRITCH. 3. may be ZIM. And 19 is probably LAY. Let me know if you figure it out.
Clancy12: 3-D is ZPM.
MattEmAngel: 13-A is SUPERGRASS.
Clancy12: Yeah and 10D is Bart. We have the whole thing solved except for 19A.
MattEmAngel: The fact that "Power lines?" ends in a question mark means it is a play on words. Lines can refer to dialogue. It is absolutely not physical power lines that carry electricity. The only obvious word is "LAY" but I haven't found a connection.
Random Stranger: 19-A is LEY. You know, like ley lines. That New Age supernatural geomancy fairy voodoo with supposed spiritual power and mystical energies?
Random strangers didn't hurt either.
The highlighted squares contained the letters "ADEEEEHHINORTTTTU", but what did they mean?
Random Stranger: Have you guys seen outside? The rabbits are aplenty.[4]
_____
Footnotes:
[4] Obviously, this stranger wasn't very random.