I'm more in favor of the implication than the alias. Dawntrail spoilers up to 7.2:
Relating to the different versions of Sphene
1. There is the first Sphene encountered during Dawntrail. In patch 7.2, the characters decide to start referring to her as "Endless Sphene" to differentiate her from the other Sphenes. I think this is the Sphene that queen_sphene is referring to?
2. At the end of Dawntrail expansion, Endless Sphene is fought as the final boss. Her boss form is named "Queen Eternal". This would be sphene (boss) (ff14).
3. There is the impostor Sphene encountered patch 7.1, whom the characters decide to label as "Simulant Sphene". She looks identical to Endless Sphene and only differs in personality. It probably wouldn't be worthwhile to have a separate tag for her, so maybe also tag her as queen_sphene.
4. In 7.2, the original still living Sphene is introduced as an NPC and is simply called "Sphene". She wears a more modern, cyber-punky outfit and I think may be distinct enough to have her own tag.
With the above, I think it would make sense to have queen_sphene for 1 and 3 above, create a new tag for 4, and then have both of them implied to sphene_(ff14). And 2 I think is separate enough to be kept on its own