Although I have not played the event where she stars, a video I saw and the wiki page (Anchira redirects to Andira as well) suggests that the official translation is Andira, not Anchira. It also fits with the Buddhism theme naming for the new year special characters (Vajra, Mahira, Anila).
So requesting changing the tag to Andira, though Anchira should still be put as an alias for the tag.
Edit: Or would aliasing Andira under Anchira fit more, considering Danbooru's policy of using the Japanese name? I'm not sure since I think it's possible to romanize アンチラ as Andira as well. Either way, I think Andira should be added to the tag either as alias or renamed to Andira because official translation says it's Andira (I was really confused when the only Andira I could find was was andira_(buddhism) and an andira tag with only a Touhou fanart in it).
Updated by FengLengshun