There's more than one round?Dooku's experince doesn't exceed Kas'im's by a ton actually. Take the 10 years between TPM and AOTC for example. Dooku did relatively little, if any, fighting during that time. Kas'im has likely fought and killed HUNDREDS of Jedi in fights to the death. Kas'im spent nearly every waking moment improving his combat skills. His dedication to lightsaber combat is much stronger than what has been shown in anyone else. If Dooku has more actual training time than Kas'im it's not a lot. And as we all know, experince isn't everything. The fact of the matter is that even if Dooku knows some elements of every form he has not MASTERED every form. As far as we know he's only mastered one.
Proof he killed hundreds of Jedi? We have actual victories attributed to Dooku. Many. They've been listed and are fact. I would like some corresponding fact to your claim Kas'Im killed hundreds of Jedi. Or even 10 Jedi. Or even a single Jedi of those mythical hundreds that was on the level of Yoda, Mace, Sora Bulq, Vos, or the rest.