This question was recently migrated from Spanish.SE to Stack Overflow en español. The migration notice in the outbound question (accessible with the URL option
noredirect=1, or seemingly also accessible by default without that option to Spanish.SE moderators) says:
This question was migrated to Stack Overflow en español so that it can be answered in the desired language.
It turns out that migrations from Spanish.SE to Stack Overflow en español (which do happen once in a while) are not done "so that the question can be answered in the desired language", as both sites allow answers in Spanish. These migrations happen because the question is about programming instead of about the Spanish language. I guess also that migrations from (any site other than Stack Overflow) to Stack Overflow en español are not necessarily done only for the reason stated in the migration notice.
Can the migration notice be updated to be similar to the standard message for inbound migrations? Something like
This question was migrated to Stack Overflow en español because it can be answered there.