Assigning BIP numbers itself is easy enough. The hard part is evaluating
if the new proposal meets the criteria - which definitely needs dev
skills (mainly for technical soundness). So IMO we should move forward
with more editors ASAP without waiting for a new way to coordinate the
numbering (we can deal with that later/in parallel to solving the
immediate need).
While I think having BIP editors who can go through the backlog of
PRs that modify BIPs would be useful, I think the primary complaint
recently has really been on the assigning of numbers and
subsequently getting those proposed BIPs merged. AJ's original email
began with a discussion of open proposed BIPs that were (presumably)
waiting on numbers. So I think adding editors who can assign numbers
should be something we do sooner rather than later.