This has come up a few times here before.
The prevailing wisdom has always concluded that its advisable to have a separate will for each jurisdiction.
If there are two wills, then both wills should refer to the existence of the other.Each will should clearly state that the will refers only to assets in "Ireland" or "France" as the case may be.
It is possible to have all the assets mentioned in one will. One big downside of this approach is that the original will can only go through probate in one country at a time and that can severely slow down the administration of the estate