Casse heavy units ?

I currently held a Casse campaign in 244 BC, have done all MIC but could recruit nothing more than the Botroas and Chariots, and could have build mines only in ONE province.

I must wait for some reform at fixed date, or something like this ?

Yes. Celtic Reforms.

And mines are entirely province-specific.

You should be able to buid the early champion units (Calawre and Cwmyr) at least. If you can't, that's probably a bug.
The first reform (220 BC) unlocks a couple of units: the Kluddargos (champions with dual-handed swords) and the Belgae Milnaht (non-champion heavy infantry, quite good but not so much armour)

It's been a long time since I last played Casse, but I don't remember having serious financial issues with them despite not having many mines. Since early on you're only fighting against Eleutheroi, you don't need to support a lot of troops.

Dates here, incidentally.

Oh I have absolutly no financial problems with the Casse, bringing something like 20 000 mnai every years to the Aedui and Arverni for they fight against Rome...it xas just a question.

I couldn't recruit the Champion, no, my only npn-basic unit accessible is the chariot.

The Calawre, Milnaht and Kluddargos are available after the reforms the Cwmyr are available from the start in the midland provinces north of your capital. And the Batacorii in the two Belgae regions in Gaul.

Thanks for all !
So it's normal I can't hire champion in Camulosadae.

Yup. Well, I guess the charioteers can be regarded as "champions" of sorts (did they have the "command" ability ? I forget), but hardly "heavy" units...

They did in 0.8, anyway. Lots of stuff seems to have been changed since then, Calawre used to be available early on. Batacorii and Milnaht (post-reform) used to be available in Camulosadae as well.

I tought batacorii were still.

Naw. Standard Gaeroas only, far as I recall.