Do European countries regulate muzzleloading firearms?

Some do, some don't.

They're regulated here, unless they were made before 1890.

So inline type guns (primer ignitioned) are regulated in Europe?

In some countries, yes.

Thank you

In France replica of antique (pre-1900) black powder handguns and rifles are considered firearms but are available over the counter. Just have to show ID to show you're > 18.
Not just muzzleloaders. But no metallic cartridges though (which would make it a "modern" handgun or rifle like a Glock or a Rem700).

Which means a BP Adresa Vortek muzzleloader would probably be considered a modern gun (like a Remington 700) which can he had under a different set of provisions.