NickB

I have never used shopformiles but it looks to me that it operates like a referral site (like topcashback, quidco, poulpeo or, to take an airline example, the British Airways e-store). If that is so, you still book on the LCAH website. IME, such bookings via referral sites are never treated as bookings from 3rd party. That would be extremely unusual for Accor to deny normal accrual rules.
If you look at the rate of accrual, it is not especially generous anyway if you compare it to sites like topcashback or quidco, where the standard cashback is 10% for Sofitel, Pullman, etc... and regularly more than that during (frequent) promotion periods. Using topcashback or quidco for my accor bookings has never led to the denial of Accor points or perks.

What has happened more recently, on the other hand, with some programmes (such as HIlton or the hotels.com programme) is that the rate of accrual on referral sites has been lowered if you book your stay as a member of the loyalty programme. So, what would be more likely to happen if it is indeed the case that referral and earning accor points are incompatible, would be that the FB points would not be credited desipte going via shopformiles rather than the other way around. As I said, however, given that the shopformiles offer is not particularly generous and signfiicantly below what is available through other referral sites, I would be surprised that FB points would not be awarded but you never know...