Do ACARS messages technically include information about lon/lat position?
No
Could ACARS messages technically include information about lon/lat position?
Assuming, that no VHF coverage is avail. ACARS is communicating via SATCOM. To contact the satellite, the A/C has to know his position in regard to the satellite to adjsut the dish.
ACARS is linked with most of the computers , so it should be easy to track it by sending LAT/LON datas.
Are the ACARS messages that have been published truncated in a way that would suggest Air France to have additional information about exact position transmitted by satellite?
Maybe, but till now all flight trackings are based on OOOI messages and calculated flightplan. I think there are also some legal issues.