Pacto da corrente diz (texto em negrito meu):

You learn the find familiar spell and can cast it (...)

When you cast the spell, (...) choose one of the following special forms: imp, pseudodragon, quasit, sprite

A mágica Find Familiar diz:

You gain the service of (...) a spirit (...), the familiar has the statistics of the chosen form though it is a celestial, fiend or fey (your choice)

If you cast this spell while you have a familiar, you instead cause it to adopt a new form. (...) Your familiar transforms into the new creature.

Um Pacto do Bruxo de Cadeia que tem um familiar celestial lança o feitiço novamente e assume a forma de imp? Seria considerado um celeste?