I stumbled onto this post[1] from Maciej on the mostly-quiet pinboard-dev group:

"...I've moved back to Pinboard work now after a two-year detour into US politics, which I hope will lead to a much less frustrating experience for my customers. It will take a little time to work through the backlog, but that is what I am doing now and into the forseeable future. My apologies to everyone who has had a hard time getting support from me since autumn 2016."

So, fingers crossed that our favorite bookmarking service will get some attention after a 2-year hiatus.

[1] https://groups.google.com/d/msg/pinboard-dev/1AHU0crTL3M/pr_7dTPvCwAJ