Okay, I tried translating it ^^
But well, the kanji lyrics aren't out yet, so I was kinda guessing what she was saying. Plus I always abuse the dctionaries when translating songs ('cause my japanese sucks XD) and without lyrics it's hard XD
But anyway, here's what I got:
Spoiler:
Thank you, mama
thank you, mama
having met you is what happiness is
A worried crying face
a voice that's a bit low
(blablabla... dunno what she says here XD)
all the different "me"s
more precious than any miracle
a treasure called "you"
Thank you, mama
crybaby mama
you're inside of me
Thank you, mama
you stayed by my side
I was born so that I could meet you
a quarrel at midnight
I left home
and kept on waiting for you to come
becoming honest using words
if you hold me, I'll understand it right away
Thank you, mama
mama who pretends to be strong
I'm inside of you
Thank you, mama
you taught me the meaning of happiness so many times
I wonder if someday I'll protect someone like this
Thank you, mama
thank you, mama
for being here
Thank you, mama
thank you, mama
I'll always be happy*
*This is probably a play with words... "mama" means "way" or "manner" in japanese, so when she says "shiawase no mama" I think it's like, "in the state of happiness" kinda thing, playing with the word "mama" meaning "mum". Otherwise it would mean "I'm always a happy mama" which wouldn't make much sense.