Update spanish translation of birthday string

Would it be possible to allow translators to change the date format used in the cakeday list for their respective languages?

In Spanish at least, it’s incorrect only in some places.
It says “11º octubre”, which is a direct, and wrong, translation of “October 11th”. It should be “11 de octubre”.

I haven’t been able to find a way to change the formatting for this date just for Spanish (there’s no such string)

Some screenshots so you know what string I’m talking about: