English translation

Haŋhépi kiŋ wašté is not "tomorrow will be nice"
Haŋhépi - night
kiŋ - def article
wašté - good. thus; the night is good (lakota is pretty much "to be" for pretty much everything so there is no word for "is" neccesary to convey to be)

Čhaŋté wašté hokšíla l-akhé ištíŋma
Čhaŋté - Heart wašté - good, again
hokšíla - little boy
ištíŋma - fall asleep
l-akhé - I am unsure what this one means and I'll have to ask other speakers about this, different covers of the songs change the spelling of what is uttered here so it makes it difficult to discern though the general meaning of Čhaŋté wašté hokšíla l-akhé ištíŋma, is "good hearted boy go to sleep"

Ah hí yé, yo hí eyá Wé yeló eyá. - these parts in the song are more of just joik, it doesn't mean anything, if it did as Wé means he/she/it bleeds and yeló is a statement made by a man though I doubt it means that but again I will double check with others, but certainly it does not mean "I am speaking to you"