I might be misremembering (it's been a loooooong time since high school French lessons) but iirc the ma/mon address depends on who you're talking to, so if he's talking to a woman (or a lioness, I guess), then you're right, it'd be ma lionne (hilariously, the French word for lion-as-in-male-lion is... lion. Did that not sound foreign enough for LKH?). So unless "Impressive, ma petite, mon chat, mon tigre" is addressed to different people, then... well, no, he can not speak French :P