Italian to English Tech/Engineering Management transformers

This is a text describing the design and planning of an expansion project for a hospital. In a letter, the architectural/engineering firm handling the design goes into a long explanation of the approach taken, the contributions of the people involved, etc. etc. At the end of the letter, out of the blue there appears a term I've never heard of (which shouldn't have suprised me, since many of the words used in this wordy presentation were a product of the writer's imagination). Here's the end of the letter, which contains this strange term:

Affresco complesso e affascinate, quindi, al quale hanno contribuito con un prezioso bagaglio di idee, conoscenze e suggerimenti tutti i colleghi del gruppo di lavoro predisposto dal Raggruppamento incaricato, come pure tutti i tecnici e gli amministratori degli enti intervenuti, ai quali va il nostro più sentito ringraziamento.

Ing. Tizio Caio
Presidente Studio XYZ
Capogruppo del Raggruppamento incaricato

Perhaps a good translation would be "professional group assigned to the project". What do you think?

Thanks.