This article identifies deficiencies in the article of Bernauer et al. (2020) in performing and describing shake table and numerical (synthetic) testing of newly designed seismic instruments for recording complex translational and rotational motion. In my opinion, this is a result from a deficiency in referencing previously published peer‐reviewed papers in this area. I also disagree with Bernauer et al. (2020) interpretation of the origin of errors in a vertical sensor’s recording because the sensitivity of a vertical pendulum type sensor to small tilts is much lower than that of the horizontal. Complete differential equations of pendulum‐type horizontal and vertical seismometers are presented and examples of previously performed numerical and shake table tests of seismic instruments are shown.