At my local track there is a section where you have a right curve at the top of a crest
(turn 9 at Calabogie full track). The car gets a little floaty in the front end and it can
make the car unsettled in the braking zone for the next corner.
Would a front splitter help with keeping the front end planted?
Probably yes.
Don't expect wonders, but undertray + rear axle cover + splitter will at least reduce
aerodynamic lift by some amount thus adding grip at high speed corners.
However, suspension mods will be neccessary to give a greater improvement, say
sway bars + dedicated coilovers + bushings + roll center correction. If you suffer
from understeer, add front camber, if you want more overall grip, get better tires.