BATAX breaks other vocabulary selections

Issue Summary

Thanks to a modification proposed at #552870: Breaks CCK Nodereference Autocomplete Fields I can get BATAX to work with other CCK autocomplete fields in a submission form. However, when I edit nodes, any previous selections from any of the multi-value [non-BATAX] vocabularies are erased. And with new nodes the form submission/validation seems to work for all vocabularies, but anything in a multi-value vocab is not stored...

Example:
I have a content type which has following vocabularies:

1. a compulsory vocab of Audience (which can have 'Unlimited' taxonomy terms selected). Because multi-terms this vocab is not BATAXed
2. An optional Curriculum subject - which is a single term; this is a small vocab so is also not BATAXed
3. An optional Clinical classification - which a large vocab of a single taxonomy term; this is picked up by BATAX

Any selections in vocab 1 (multi; non-BATAX) are validated on form submission (ie recognizes that at least one term has been selected), but are not stored
Selections in vocab 2 (non-BATAX) are stored correctly and
Selected in vocab 3 (BATAX) are stored

I'd never gotten far with BATAX due to the breaking of CCK, so I only managed the above with the code tweaks proposed at #552870-4: Breaks CCK Nodereference Autocomplete Fields. So this behavior is only shown with the modification implemented; BATAX affects many other form elements without the modification so I've not been able to test it without it. Not entirely sure if the hosing of multi-value vocabularies is a core problem with the formal release of BATAX, or the tweaked version. And there is no DEV release to assess.