Name "妲己" read as Dájǐ (Daji).
Is there a reason for the current translation (dakki) of the tag?
In favor of using transcription, I found examples of use, but there are no suitable search results for the current variant.
Should create an alias or rename a tag?
Dakki is the Japanese pronunciation of 妲己. The name pops up every now and then in Japanese copyrights for a kitsune/fox spirit character, especially if she is Chinese themed.
A common translation convention for characters with Chinese names (especially historical/mythical Chinese names) is to use the modern Mandarin pinyin transliteration even if the character is from a Japanese copyright and has their names pronounced/spelled only in Japanese. This is also, IIRC, Danbooru's current favored policy, as seen in forum #28725 and forum #28786.
As such, I would also agree with making Daji_(Monster_Strike) the primary tag. Especially since this Daji/Dakki seems to have her name spelled consistently as Daji in most English sources, including Pixiv translated ones (unlike a few other 妲己 who get transliterated consistently as Dakki instead).