As long as the connections made are soldered and correctly paired to the right wires that should eliminate any connector issues, its similar (but not as neat) to what I did on Mrs Ffoxys 1.2 but we still own that before any smart-arse asks!
If there is still an Airbag failure warning and the connections are good it may be the OCS mat in one or both of the seats, or one of the many other connections to various Airbags, depending how many you have (model dependant).
There is a good guide in the Stilo section for checking I think.