The question becomes one of politics: how much does each EU member care? I'm reminded about the old joke about the difference between ham and eggs being that the chicken is involved but the pig is committed.

Poland, Romania, and the Baltic states are "committed" in that they regard the risk of a Russian invasion as real, and have seen occasional incursions by Russian flights and even missiles. If it comes to a fight between self-defence and the deficit limit, they're just going to have to break the limit.

Germany, on the other hand, has been very comfortable taking Russian bribes and gas, as well as being uncomfortable with re-arming, so they've been lagging behind on the project.

Maybe there will be another "incident". France has already been reporting attempts of sabotage against their railway network.