As I understand from apartments we have owned, communal charges are agreed by the committee elected by the co-proprietors, advised by the syndic, and proposed, and voted on by the co-proprietors, at the AGM.
They are not negotiable on purchase; they are decided by the co-proprietors, and are the responsibility of the prospective owner, and the seller has no influence over them. It may be possible to proportion them over the year when buying by agreement with the seller.
Edit: In the case of a new build, the apartments may not all be sold, so that fixed charges may be divided by a small number of owners, resulting in the communal payments being unusually high.
Another pitfall is that there is a tendency for absentee owners not to pay their share of the overheads, but as these are generated by bills which have to be paid, the burden falls on the other owners to pay them.
You should get a copy of any and all the agreements and rules affecting the property before you buy. I suggest getting a Notaire to advise you on this.
On some great and glorious day the plain folks of the land will reach their heart's desire at last, and the White House will be adorned by a downright moron.
H. L. Mencken 1880 - 1956
Some may not like his views, but what a prediction!