Hello @Sara,
my issue (Dashboards/Dashlets) is still open.
They work in 2.0 and 2.1 but not in 2.2 and are not failing because of Werk #14297 (which was listed above).
The documentation how to write own Dashlets is stilll missing. The copy and modify approach did not work here. The problem here is, that it is not only the moved libraries, but a huge change in the structure how dashboards and dashlets are organized (init, register, link).
I know that this looks like a very special edge case, but I would be happy to talk to someone from Checkmk about that case. Perhaps at Checkmk Conference?
Kind regards
Stefan