I can confirm, after receiving a response email from Support, the
[Error] persists and am unable to produce a redeemable key.
At this point I am not sure it makes a difference what the titles are(these being part of a marquee sale), but for thoroughness,
I purchased
Contra &
Castlevania A
nniversary Collection(s), as well as
Super Bomberman R.
The emai I received was highly personable (presumably automated, if not a "template" response) and consisted of this, verbatim:
Hi,
Please try again now.
Thanks
I remain patient, optimistic, yet eager. It has given me pause to reflect on the nature of impulse purchasing, haha...and whether these "HELP" forums are navigated by moderators or some variation of consumer support/customer service XD
Indeed, I think we're here to offer one another some form of positive morale. In seriousness, I do hope everyone is getting taken care of and, soon, any frustrations you're having are alleviated!

I am on day 2 and some hours past purchase...have any of you others having errors/problems been waiting 3+ days?