I think those 2 get vet way too fast. early game a jester can still take out several engies while under fire by 2+ mobile AA, then fly off and continue killing and getting its health back quite fast. I propose setting vetlevels to every 5 kills
Later a first ML will have no problems vetting up several times unless you can counter it early with your own exp. Factors are:
Typically first exp thanks to lowest cost and fast movement speed, facing and eating "regular" armies
DPS is twice as high as GC,
Vetlevels are after 25 kills, GC takes 50.
Means it levels 4 times faster than a GC, which gets higher healthboosts so its ok that a ML levels somewhat faster, but 4 times faster ??? How often do you see a GC getting saved by vetlevels, how often a ML?
Id propose to rasie vetlevels to every 50 kills for the ML, it still has the most dps and beeing the earliest+fastest exp, but this should allow the opponents to actually wear it down with their existing T2/T3 forces.