Don't add the umamusume tag to original/delusion of umamusume personafications. JP artist already don't use the tag aside from the オリジナルウマ娘
The thing is though, the personification concept seen here (and elsewhere post-2018) is very much derived from Cygames' take on personifying racehorses. I wouldn't have added the Umamusume tag for a simple personification in which Pubo retains his original gender, but posts like this (or other posts which follow the general constructs of Umamusume's takes on personification) warrant an Umamusume tag...
... Last but not least, Kopperion herself (or himself?) even put "original Umamusume" in the artwork itself so it's clearly not something totally independent from the Cygames IP. Otherwise the term "競走馬擬人化" (personification of racehorses) would be used.
