Fedele, I just looked at the links you provided and saw the full text of the song. Great stuff; I never knew there was a Welsh choir dedicated to songs of protest! Anyway, I'm going to give you a very loose translation but take it with a large grain of salt before you start your translation into Italian...

Drylliwch y cyffion, daeth yr hyfryd ddydd
Fe ddaw gweithwyr Cymru yn weithwyr rhydd.

Shatter the chains, the beautiful day will come
When the worker of Wales is a free worker.

Dewrion y lofa a'r peryglon mawr
Fechgen y chwarel, daeth eich awr
Dowch o'r bythynnod i'r fuddugol gad,
Y mae chwyldroadau'n siglo'r wlad.

The brave man [ ] and the great dangers
Young men of the quarry, your hour will come
[ ] from the cottages to the victorious army,
Revolution is shaking the country.

Tyrfa'r heolydd, prin eu bwyd a'u gwaith,
Swn buddugoliaeth sy'n eu hiaith;
Y mae'r deffro'n cyffro tyrfa'r stryd,
A gwerin Cymru yn arwain byd.

The multitude on the roads, scarce their food and their work,
A victorious noise will be their [ ]
Excitement is awaking in the crowd on the street,
And the people of Wales are leading the way.

Disgyn gwrhydri'r tadau ar y plant,
Esgyn gobeithion y byd o'r pant
Anthem y Chwyldro sy'n atseinio'n groch,
Un yw gwerin byd dan y Faner Goch.

The fathers' valor descends to the children,
The prayers of life ascend from the valley
The anthem of the revolution resounds loudly
The people will be one under the Red Banner.

Okay, all you Welsh speakers, you can stop laughing now, I did my best! The brackets represent words or phrases for which I hadn't even a best guess, I hope someone can fill them in.

Meanwhile, this has been a fun effort and I thank Fedele for bringing the song, and T. E. Nicholas, to our attention. Margaret