hello Arrow,
try putting back to the old tracer textures into the fxtextures folder. This is a common problem with the newer aircraft and if you look at the threads this issue pops up quite a lot.
The installation instructions for the spitfires IIRC tell you to modify a couple of lines in the effects.xml. If you add the new textures and modify the effects.xml as instructed, the new tracers should appear. The problem is, some older weapons will not show their tracers.
So you need to make a choice between keeping slightly older look to the tracers, or getting nice new tracer effects but some older guns having tracer that does not work.