Issue preventing proposing [expresiones] tag as a synonym of [modismos]

Question

Given expression is a synonym of modismos (and this previous meta decision to synonymise such tags), I tried to propose expresiones as a synonym of it as well.

However I got the following error message:

It seems that modismos had previously been proposed as a synonym of expresión before its merge with expresiones, and this proposal has persisted behind the scenes, blocking the reverse association now.

This bug has been noted a few times before: Tag synonym for 'edit', 'edits' and 'editing'

Can this be resolved (as per the actions in the above SE Meta post), i.e:

• Reverse synonym expresión → modismos and merge
• Add synonym expresiones → modismos and merge?

Answer 1

The UI of Tag synonyms is a bit poor, so there are always some subtleties to take into account. In this case, the situation seems to be like this:

• expresiones is already a synonym target for two other tags: expresión and fixed-expression, as seen in 'expresiones' Tag Synonyms.
• The synonym creation does not allow suggesting a new mapping (A -> B) if the source (A) already has some tags pointing to it. That is, if A->B already exists, you cannot do B->C unless you remove A->B.

For this, the solution would be to:

• Remove the synonyms expresión and fixed-expression from expresiones.
• Create the synonyms expresión, fixed-expression and expresiones pointing to modismos.
• After a while, merge. Not instantly, since a merge cannot be rollbacked.

By the way, some mapping are not necessary: as seen in the Tags list we now have expresiones, expresiones-fijas, expresión, expression, fixed-expression, and fixed-expressions. There is no need to have all the tuples singular-plural, since they share a big part of the initial characters and user interface suggests tags based on the characters you type and match the beginning of the tags' names.

See What are tag synonyms and merged tags? How do they work? in Meta.SE for more info.