I doubt Devin could write an integration for an underspecified legacy API like that. Whenever I have had to, I've needed to talk to support/engineering on the other side.
that's definitely still the case. devin drafts my emails for issues it runs into (which i tell it to do) and i send them off.
this is definitely slower than if i were doing it full time, but i run a company. i go from customer meeting to customer meeting and spend 5-10 min a day taking whatever is blocking devin and pasting it into an email to the partner to get a response for devin.