In addition to the last answer, which seems a potential way ahead…
If I understand, I think you want the the pop-up value list of AttributeB to be populated dynamically from AttributeA’s values. If so that also implies you’d need to seed the suggested values for AttributeB.
So, I don’t think either of those is possible But, whilst I’m not aware of any way to automatically set suggested values for an attribute. But assuming you can access the values of interest you could set them all for one particular note as that would then seed the values into the pop-up list of used values.
[Edit follows with additional points]
Bounding the use case here, is AttributeA a single value attribute (e.g. a String-type) or is it a multi-value (List or Set types)?
Something I’d missed earlier is an extra complication, that of changing AttributeB’s suggested values on the fly, based on the current seed value selected for Attribute A. This certainly doesn’t appear possible at present. At present, a possible attribute-based method would be to make a discrete attribute for the synonyms of each AttributeA stem term. But I’m sure that isn’t what you are after as you’re end up with >100 attributes and I’m guessing you want a solution that works in Displayed Attributes.
Essentially you are looking for a mechanism of cascading lists as used in some databases where the second list is re-populated to reflect the selection in the first list. I don’t believe that is [possible at present.