I mean by messages the text that shows up on the messages (example: There are new posts in the forum thread: Bug)

The message text appears to be defined in https://github.com/scratchfoundation/scratch-www/blob/develop/src/views/messages/l10n.json.

Voxalice wrote:

The message text appears to be defined in https://github.com/scratchfoundation/scratch-www/blob/develop/src/views/messages/l10n.json.

Thanks! But now I want to find them again but in Italian.

alboxer2000 wrote:

(#3)

Voxalice wrote:

The message text appears to be defined in https://github.com/scratchfoundation/scratch-www/blob/develop/src/views/messages/l10n.json.

Thanks! But now I want to find them again but in Italian.

I'm not sure, but I think the most likely place for that would be in Scratch's Transifex page, outside of scratch-www.
You can find a guide to access it here: https://scratch-mit-edu.ezproxyberklee.flo.org/discuss/topic/430514/