Pine will accept it (on a per-session basis)- you just have to click past the warning. I believe it’s also possible to import the certificate, but that’s a bit trickier.
Unless you’ve overridden the default inbox-path or folder-collection by hand, you do not need to make any changes.
We have already added /novalidate-cert to the global config. If you don’t have inbox-path or folder-collection defined by hand in your .pinerc, please contact support if you’re still having this problem. One reason we maintain pine.conf separately is so that we can make changes to it if necessary.