A sad coincidence but I have EXACTLY the same problem.
I sourced a pair of replacement front wheel bearings from GSF car parts who re-assured me they had supplied me bearings for the Mk1 Laguna with ABS.
I dragged out my 'scope and checked the presence of wheel pulses on both front wheels. As far as I could tell they were present and at the same level as the pulses coming off the rear which had not been replaced.
One thing I kick myself for is I ran the motor on the axle stands at idle with the wheels off to check for any
leak from a new left side driveshaft inner gaitor. I remembered I had drawn the pads back a little to ease them back over the discs, so I touched the brake engine running to close them in before test driving. There was an immediate clunk and stall as I suspect the servo reacted more than I expected. I am not sure if the SERV/ABS lights were on before I did this or not.
This is such a painful job to do that I am reluctant to take the hubs off to try something else as first line as I now have both fronts with new bearings.
The SERV/ABS lights are now lit at key on when they went out before. OK they do go out and come back on as TTT said when the car is driven, but it seems to me the ABS computer has now stored a fault code which cannot self clear by driving.
TTT, I would like to see the follow up to this and I do not know how close you are to digging further. In the meantime I can only think that a diagnostics scan is the first thing to get done. After clearing all fault codes, if it then comes back with front wheel sensor faults then I am inclined to suspect the bearings, but I cannot understand this when I am getting wheel pulses.
The only fly in the ointment is if Renault have ever used different pulse counts per wheel revolution in these bearings and now my fronts are incompatible with the rear.
The pulses coming off the sensors are quite frequent. For example, I can rotate the disc less than 25mm at the circumference and see the pulse change voltage polarity. Referred to 10 volts, the pulses are about 1 volt amplitude i.e changing from 10 to 9 volts as you rotate the disc by hand.