The Mongoose OS licensing page should call out that mJS is licensed under GPL v2. There doesn't seem to be a linking exception for mJS, at least anywhere I can find. This means that if you use the community version of Mongoose OS and mJS, then your app your distribute would need to be licensed under the GPL as well.
To be clear, I have no issue with this, but since mJS is talked about as one of the ways you can write code for the OS, and it isn't explicitly called out anywhere I can find, and may come as a surprise
More to the point you don't even seem to have a linking exception in either license would could raise some potential issues
Which then raises the question, if I license the commercial version of the OS, does that come with a license for mJS, or would one have to license that as well?