Vertimas - Švedų-Anglų - HÃ¥ll tummarna! Imorgon kommer tillsynsmyndigheten pÃ¥ besök... (hua) mÃ¥tte allt vara ok.

vad 'är hua ?

Håll tummarna! Imorgon kommer tillsynsmyndigheterna på besök...hoppas allt är som det ska.

"HÃ¥ll tummarna!" translates better as "keep your fingers crossed" ther is not such an expression with your thumbs in english

tack för tipset! jag vet inte vad en hua är?

It looks like s/he was swallowing a frog.

Now serious:
It really sounds like a simple interjection.

Yes...the meaning of 'hua' is like swallowing a frog. I could not say it better... It has to do with something you say when you did not like it, are a bit affraid,, maybee...gulp or something. If 'gulp' is a english word?