HK immigration take a dim view of work visa applications if they know that the applicant is already in HK. Don't ask me why, but they do. I guess they take the view that the applicant is adopting the "better to ask for forgiveness than ask for permission" approach.
Yes, I know some people start the application process when they're already in HK on a visitor visa but the application form asks for their home address overseas and assumes that they are not applying from within HK. And yes, some people may well have been successful with this approach but there is no guarantee of success. If the individual case officer handling an application sees or suspects that the applicant is in HK he/she may demand to know why and may be pissed off at the effrontery of some foreigner taking the piss out of a system that requires work visa applicants to start their application process whilst in their home country.
I understand that the application may be processed and administered by the sponsoring HK company, but the company is not the applicant. So, to clarify my original point, if the OP's husband is going to come to HK on a visitor visa and work, which is illegal, he should ask his employer how they will remunerate him whilst he and his family are "tourists" in and therefore unable to open a bank account, while HK pretending to be making the work visa application from France. I say this as someone who processed work visa applications both when HK was a British colony and as recently as 2014 and I know that it is not advisable to get this wrong.
Transferring from a job where you already have a work visa to a new position with another company is usually tolerated but it doesn't have to be and so it is not guaranteed that it will be approved.