"were less understood" is a correct and usable phrase in written English
You can use it to refer to a past event where something was not understood as much as it should or could have been. For example: "The implications of the findings were less understood than anticipated."
However, there were concepts that they highly understood as well as concepts that were less understood.
For the researcher, who worked in a psychotherapy ward where most women were living with borderline personality disorder, the care of these women was of vital importance, as they were less understood by mental health care providers.
The participants generally demonstrated a good understanding of the risk factors associated with developing skin cancers, although some frequently occurring features were less understood (Table 3).
(Provincial Health Officer, Female) The different payment schemes for the poor including use of health equity funds were less understood especially by health workers at the grassroots level as the following quote helps to illustrate: "I have never heard of the Health Equity Fund.
What is less understood is the role of technology in turning the theory into reality.
How could something so big remain unseen for so long — or be less understood than dinosaurs?
It is less understood that listeners have their own development to consider, as well.
What is less understood is the extent to which a complex combination of secondary factors contributes to the decline.
First, salt is harder to scrub from the food supply, and its connection to cardiovascular disease is less understood.
As a result, small tornadoes are not well documented, and in many respects they are less understood than stronger events.
The biomechanical effects of swing weight interventions are less understood.
