Same secret for their airbus series probably 
CRJ have Rockwell Collins avionics and its probably the problem to synchronize the buttons who are outside for selecting the weather, terrain and zoom. Its not same for G3000 or GNS530 mod where the buttons are integrated in it. Its my opinion.
The CRJ uses C++/WASM which has no weather radar support.
Well this sucks no auto land 
I didnāt know it
What is the relation with weather and terrain radars ?
There are no C++/WASM APIs for weather data or weather radars.
It is only available in JS and itās still very limited there.
Ok that explain the problem with FSX/P3D version too. JS as workingtile use could solve the problem ?
Yes. FBW and WT both use JS for their avionics.
However it is really not that much better, the radar that does exist in JS is very limited (hence why FBW is removing it and asking for better solutions) and unrealistic.
Itās up to MS to work on further improving the weather radar APIs.
Finally JS is a patch for MS weather and terrain problemā¦