The Auto subbing has been changed (for 2 seasons at least I think) but Support are currently remaining quiet on the topic of 'selection criteria' and 'does the Engine-managed Auto-subbing on mobile platforms over-rule the preferences in web platforms?' and marked my Question as solved.

I got the big stick out and poked them again but it probably won't make a difference.

Maybe others can try too or a passing dev/admin might think of doing an Improved Auto Subbing feature post.