First quote, I solemnly swear that I am up to no good.

after I put it through French, Spanish Gaelic, Italian, German, Arabic, Chinese, Greek, Latin, and Swahili I got, I'll get my hand, I can not.

well, that makes absolutely no sense.

Here's the second one. Happiness can be found even in the darkest of times if one only remembers to turn on the light.

I had to put this one through a lot of different languages to really get it to change. In the dark, it is easy to remember goodness.

I don't really think that's true.

the next one is, You're just as sane as I am.

After I put it through a bunch of different languages including, Chinese, Polish, French, and several others.  Because I'm like power

the next one is. The ones that love us never really leave us.

after I put it through Norwegian, Chinese, Thai, and several other languages. People will not let us go.

The next one is, You're a Wizard Harry.

after I put it through a lot of different languages. Harry, this is a guide. 

Well, the only thing that didn't change was Harry's name. and what would Hagrid be giving Harry a guide for?

the next one is. what's life without a few dragons?

After google translate screwed it up. What is the beauty of my love?

well, that changed a lot.