When trying to add a Node Module over the Plesk JXcore Interface it fails with the message. I can't even access the jx command over SSH.
error: Cannot install sails module. Wrong user id of the command.
Today, early morning, new version of JXcore support Plesk's extension was published: 0.2.0.
Among many things there are some improvements related with NPM modules installations, also your case with "Wrong user id of the command" was taken care of. This wasn't a bug actually. Rather a result of redundant permission check and you were the first to encounter this.
Also there is a new feature which allows to enable/disable JXcore support for entire subscription or all of them at once.