According to the bugtracker at tfbt.nuvturais.de the mixture lever position was wrongly reversed until the very last patch from 1C, which fixed that issue (before Team Fusion took over). Possibly the info-window output is still reversed...
There's a strange thing with me, when I start my Spit: The mixture will be initially (wrongly, and not according to the visible lever position, which is backward = rich) lean - until I once pressed the lean-key first and then the rich-key. After that, everything is fine and I can ignite the engine.
Got used to it.
Artist