From my own experience in California USA in calcareous soils, yes the soil test will show very high calcium but very little of it is plant available because it is in the carbonate form and it is not plant available. Different cultivars will perform differently based on their ability to excrete organic acids to release some of the calcium. In the central coast of California, high calcium carbonate (limestone) soils are actually a selling point, making for a much more distinct and chalky wine that can fetch 10x the price of noncalcareous soils. A lot of that may be unique marketing that San Franciscan wine snobs are willing to pay for, but it doesn’t need to be a deal-breaker for you. The growers tend to reduce the amount of N and K fertilizer considerably, and may even dry farm it (since we have no summer rains here, the vines rely solely on winter rains in such a system). This reduces internode growth and improves quality. The trade-off in this approach is lower yield, but they make up for it with the higher-priced wine.

The best method I know of to gradually release some of that limestone is to apply micronized sulfur to the soil to slowly start releasing more calcium. You may also find chelated calcium foliars to be effective.