Rewriting HOST+URI does not work

your irule is confusing. Do you want webfront-web.domain.com or web-webfront.domain.com?

try this:

    if { ([HTTP::uri] starts_with "/webfront") } {
         change host name option 1
        HTTP::host "webfront-[HTTP::host]"
         or option 2
        HTTP::host "[substr [HTTP::host] 1 ".domain.com"]-webfront.domain.com"

         trim uri
        HTTP::uri [string map {"/webfront" ""} [HTTP::uri]]

    }