Thanks for trying to help.
But your addon does not import the notes of the original addon. Besides, it seems not do correct the bugs either.
Here is my solution (for the original addon):

add this Userstyle for all websites, to restore the selectability of note contents:

.__myNoteMainWrapper * {
user-select:text !important;
}
(for example with the stylus addon; you could change it directly in the notes.css of the addon, but I don't know how, it would be great someone would takte this addon in capable hands).

There is no better addon for this task, tried them all.

Thank you very much for fixing this Add-On. Does anyone have an idea how I can migrate or import my notes from the old Add-On?

Hello, great, that you work on the stuff, thank you!

But ....
a)
Notes can not still not edited in FF 70.0.1

b)
Unfortunately import from OurStickys did not work.
https://addons.mozilla.org/de/firefox/addon/ourstickys

May you can have a look?

A big thank-you to yoasif, for salvaging Fabrizio Parrella's legacy; the only sticky notes extension that actually works like sticky notes!