I don't think it is. RIM has standardized their API to Java.

Ist there a site of RIM where they publish release notes and / or changelog files for their JDE?

It would be good to see what changes and bug fixes they did in each release update.

For Known issues you can see here: BlackBerry - Product Manuals and Guides

As far as fixed bugs.. I don't see any lists anywhere

Re: Useful Links for New Mobile Programmers + BlackBerry SDK!
 

If you are publishing software for Over-The-Air downloads (i.e. you create .jad/.jar files instead of .cod/.alx files), don't forget to configure your web server to permit Over-The-Air downloads to BlackBerries

Re: Useful Links for New Mobile Programmers + BlackBerry SDK!
 

I wonder how many people are using BlackBerry today. I think it has considerably lost its popularity over the last decade. I am from https://postcodefinder.net/wales/, and more and more often I notice people opt for Apple. I have been also using Apple for some years now. And I am very happy with its performance. At the moment, I am not ready to change it for anything else.

Re: Useful Links for New Mobile Programmers + BlackBerry SDK!
 

When Apple and Google restrict users who do not have their OS or the phones they want or sell then yes Blackberry and many other phone makers are lost.

Google owns Android OS. Every wonder why Blackberry was forced to move to Android on the new phones? And now the product is gone.
TCL announced on Feb 4 2020 they would no longer make Blackberry phones.

It is still possible another manufacturer will pick up the license to make new phones.