Some  external applications such as OnAir and FSEconomy may read the Wing tanks incorrectly.

The wing tank positions are reversed by a fraction on the two wings which doesn't affect normal usage of the aircraft in any way but does break the external clients.

When the old [FUEL] tank names are used to read [FUEL_SYSTEM] tanks over Simconnect they are converted by MSFS by lateral offset and are coming out wrong.

The Tristar INBD and OUTBD tanks are at the same lateral offset by design but probably when converted from floating point to decimal for the flight_model.cfg you get a very long and almost random decimal fraction and the tanks have ended up being reversed.
The example screenshots show the fuel loaded into the Tristar and the fuel that is reported to the external client  -  the Tip tanks show the Left Inboard and the Right Outboard.

 The fix would be to edit the tank positions so the inboard tanks are slightly nearer the centreline, just by an inch.

'Fixed' the problem with a small mod that deactivates the outboard fuel tanks, which I don't need anyway. Now all remaining tanks are mapped correctly.