The colors used in tag items when different from the normal state coloring are listed in the manual's appendix 1 for each tag item. Most of the colors are used in more than one place, so some thought should be put in before changing them to avoid conflicts and poor readability.
There are no "positive" capability indicator items as the represented software works the other way, only pointing out missing capabilities.
The "(unselected track)" tag item variants pretty much never display anything when there is no data. The other variants in many cases do display the field mnemonic, but it can not be customized (you can't make the mnemonics lowercase or change the displayed text, for items that don't display the mnemonic you can't make it display it, etc.)
