Alembic cache files can open successfully while still losing important data. The animation preservation check should look beyond file validity to units, hierarchy, animation, metadata, and external dependencies.
For Alembic cache, use a short representative clip to verify joint names, rest pose, frame range, root motion, and deformation. Preserve the source rig until joint channels passes review.
Compare clip names, frame counts, interpolation, joint channels, morph targets, and playback timing after conversion. Apply this animation preservation guidance to the actual Alembic cache delivery path.