It's possible to add, edit, and delete terms in a taxonomy through the user interface - but unfortunately, changing the labels on the various fields will require changes to AtoM's code itself. We do actually have some labels that can be configured this way via settings - including the word "Subject", but not the "access points" part of the label! See:
If you were going to try to change the access point labels in AtoM then this would ideally be done via a custom theme - that way it is easier to maintain over time in the future through subsequent upgrades. However, if that's not a viable option, then changes could also be applied directly to the relevant templates... the challenge is just finding all the right places (because the term is used throughout AtoM), changing labels without breaking anything, and remembering where you've made those changes for next time.
If you do decide to proceed, please MAKE A BACKUP of your data before attempting anything! And note that if you make local code changes directly in AtoM, you will need to reapply them every time you upgrade - this is what I meant by "next time" above - an upgrade will override your local changes.
For example - in the default Bootstrap 2 theme (i.e. not the new Bootstrap 5 theme overhaul available in 2.7), if you are using the ISAD template, then I think at minimum you would need to change the labels shown in quotes in the following lines:
There may be other places 9for example, where the term appears on the authority record templates, etc), but try that and see how it goes!
Note that after making changes I would suggest that you:
- Restart PHP-FPM
- Restart memcached if you have it installed
- Clear the application cache
- Clear your web browser cache as well before testing, to be sure you are seeing the changes.