Definitive? Hmmm... Interesting term, but instead, I'll try and address what you have asked context wise in some semblance of order
1. So you have to license types: CCE and Acrobat DC Continuous. While that is good it can cause headaches too. I will explain that in a moment though.
2. The Grant Offline Exception feature is covered in the Help documentation for the Adobe Acrobat Customization Wizard DC: Personalization options — Acrobat Customization Wizard DC for Windows
3. The "Allow standalone Acrobat deployment with CCE serial" checkbox, is used ONLY when you are going to use the CCE serial number to serialize your Acrobat install with that serial number.
4. Whether or not the language options are also contributing to the utterly inconsistent behavior not only across multiple computers.
Interrogative: Not sure what you meant here. Questions depending are:
- Are you attempting to use the Language installation options in the Adobe Customization Wizard DC?
- Are you installing to machines with different OS languages (e.g. German, Spanish, Italian, etc...)
Symptom 1: "It is when there are already other Adobe CC products installed when things are usually going off the rails. "
Response: OK, this probably means that you are using the Acrobat DC Continuous serial number with CCE products installed on the machine, but you need to clarify that item.
Possible Reason: The CCE serial number will generally override the Acrobat DC Continuous serial number. This may be the reason for the ODD behavior when you delete the SWIDTAG file.
Symptom 2: "On other computers, though, no matter how many times I tried that, nothing worked. I had the uninstall Acrobat DC, run the AdobeAcroCleaner_DC2015.exe util and try over. In most cases, that has worked, except on computers with PhotoShop or Illustrator installed, then those programs are no longer validated and they no longer work and I'm back to deleting the swidtag files and hoping for the best."
Response: Again, the behavior that you are experiencing sounds like you are using the Acrobat DC Continuous serial number with CCE products installed on the machine, but you need to clarify that item
Reasoning: You seemed to have missed the VERY IMPORTANT WARNING with the Acrobat Cleaner Tool
Download Adobe Reader and Acrobat Cleaner Tool - Adobe Labs
"IMPORTANT:
1. THIS TOOL IS NOT FOR USE WITH ANY CREATIVE SUITE PRODUCTS INCLUDING SUITES THAT CONTAIN ACROBAT. IT CAN ONLY BE USED WITH STANDALONE VERSIONS OF ACROBAT AND ADOBE READER. "
I hope that this information helps.