I was reading the Ars article and they mentioned the chalky aftertaste. While I don’t think I would mind it so much have you considered Calcium Citrate instead of Calcium Carbonate. It might not taste as chalky as chalk, Chalk is calcium carbonate. and from what I understand calcium citrate is a more easily absorbed form of calcium.
It’s been stated that this was a result of the rice protein in use not being fine-grained enough. An alternate source has been found and the issue will not be present in the final release.
Calcium carbonate is barely soluble and hence gives more of a gritty feel than ‘chalky’.