apm install language-xle
or a graphical installation in Atom via
Install and search for
If you detect any bugs or issues, please don't hesitate to get in contact with me, report to the bug tracker or provide a pull request for your fix. I am not sure how robust the package is, so feel free to inform me about any issue you come across in terms of syntax highlighting during your grammar development.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.