The saga is finally over! The money arrived in my Euro-based account today. And it was for the full amount which means they just had a typo in their email to me on Tuesday.

Just to recap:
48 hours after filling in the feedback form online LH said they owe me 600 euros
48 hours after that they accepted my re-sent receipts for duty of care
I emailed them 3 or 4 times after that with bank info, asking for status, etc.
I contacted LH Lurkers on FT 3x
Just under six weeks after LH's last email I wrote them one more time asking for escalation and for payment and that I would be contacting outside counsel
The next day I got an email saying I was paid.

Bottom line: they never had an issue with my bank account or my residency. They are just completely incompetent and won't reply to your emails.

Thanks again for all your help. Here's to hoping I don't have to deal with LH CS in a long time...

-RM
PS - I bounce back to Europe tomrw but I'm taking United for a change. I've dealt with EC261 with UA and they were very prompt. Of course they offer 600 euros cash transfer or UA $1,000 voucher which can arrive in less than 20 minutes.