Just as a general comment on artists, please don't anyone be shy about adding qualifiers to artists, such as pixiv url account name or homepage name.
EXCEPT for (pixiv#####). And then don't qualify things like 4st_injection, which was created as the completely useless 4st_injection_(artist). There's absolutely no chance anything ever but an artist would be called that, so disambiguating in this manner is silly, because if we ever got a clash, it'd be with another artist and then the qualifier wouldn't do anything. So yes, qualify and don't be shy about it, but use common sense and qualify in ways that will actually reduce the probability of conflicts.