You have probably already cleaned a belgian wilton using HWE without even knowing.
Make sure that all the fixings are secure, if unsure get some carpet tacks and tack down every 12 " or so leaving the head proud so that you can extract once dry.
Keep the moisture to a minimum, where sofas have been just dry vac.
There is more of a risk of shrinkage than other carpets, all i can say is i have cleaned dozens without any problem using HWE.
Mark