The answer is basically that they don't know at this point. (Reference: I did extensive research on CLT as part of a project in LA a few years ago and talked to CLT experts from the Wood Products Council)
CLT is stiffer than plywood, and the construction techniques are closer to steel/concrete, so it'll likely need reinforcement or dampering. Traditional wood buildings these days are designed to flex in earthquakes.
But it hasn't been extensively tested for seismic properties yet
True, but worth noting plywood is spiral shaved veneers which are unrolled glued with the curves counteracting This is quite different from sawn dimensional lumber. Plywood is entirely cut tangent to the grain / tree rings.
Plywood is much weaker essentially because trees evolved to withstand wind and the veneers are cut perpendicular to wind loads.
CLT is stiffer than plywood, and the construction techniques are closer to steel/concrete, so it'll likely need reinforcement or dampering. Traditional wood buildings these days are designed to flex in earthquakes.
But it hasn't been extensively tested for seismic properties yet