“Message Filter” triggers currently work only with “AND” logic. ( .) If you’d like a single job to process multiple forms, it would be best to pick out a key:value pair that is identical for submissions from both forms. As you’ve pointed out, you could achieve this by selecting a boolean that you use to group those forms together.
In CommCare, why not have a hidden form field called “send_to_job_x” that is set to TRUE for both forms whose submissions you’d like to trigger job x. Let me know how this goes, or if you’d like any additional guidance.
Also, might I suggest that you open this as a feature request here: https://github.com/OpenFn/docs/issues. If enough people support the idea, we’ll be able to prioritize it on our roadmap!