"I spoke to them in Spanish the whole time."
Translation:Yo les hablé en español todo el tiempo.
Why is 'Hablé con ellos...' not also an answer? A few questions ago had 'Hablaste con ellos...'
And Duo gives 'Les hablé montones...' which I can't figure at all.
Yes, although "con" usually translates as "with," Duo usually accepts "hablar con" for "talk to."
The above sentence has the more literal sense of "to them" by using the indirect object pronoun.
Based on what Duo has accepted in the past, I'd report it.
"Montones" is slangy Spanish that means "helps of" in the sense of "mountains of."
Also, the indirect object pronoun "les" (which is the indirect object pronoun that means "them") must always precede the predicate verb. Even when the indirect object is a noun, it still needs an indirect subject pronoun to come before the verb as well.
I was practising "hablar con ellos", then it changed to "hablar a ellos". Why?
Perhaps DL is trying to introduce colloquial variations that are not literal translations, but rather are connotative, contextual translations. See marcy65brown's comment above.
I don't understand why "Hablé con ellos" is incorrect. I find many examples of this in Reverso.