It is really kind of Trial and error. I am not sure, if that’s a problem of the 0.9 sdk. My workflow ist: Build a package, and then export your Blender model into the modelLib folder. Move the textures into the texture folder. (I usually create one subfolder for each model i try to include into the scenery).
Important ist to change the MSFS Shater to “MSFS Standard” inside blender, before you export the model.
You can then build the package inside MSFS. I could see and place every model I created. I did not manage to get it saved properly so far, everytiem I close the Package, all my models are gone and I have to start from scratch. I’ll tell you when i managed to save and build a package.