is how Peter Standish translates this (account 404 apparently in the French plan comptable) in his book "The French Plan Comptable".

I'd suggest something like this for the part of your sentence between brackets:
(changes in stocks, accounts receivable and accounts payable other than accounts payable to fixed asset suppliers)
but obviously it will depend on what terms you have used elsewhere: "purchases of property, plant and equipment" would be another possibility if that's how yout client likes to translate "immobilisations"...
Goof luck