"they were understandable" is correct and usable in written English.
You can use this phrase when you want to express that something is logical or clearly expressed. For example, "After listening to the professor's explanation, the new concept finally became understandable to the students."
Shaw's writings about music gained great popularity because they were understandable to the average well-read audience member of the day, thus contrasting starkly with the dourly pretentious pedantry of most critiques in that era.
In addition, the participants were also welcomed to suggest further comments on the questions whether they were understandable or not.
These points were then connected, using abductive analytical strategies[ 60], to the perspectives of participants, to theory and to the literature until they were understandable in the given context[ 61].
The results will be reported so that they are understandable by nonspecialists and this should help to increase the appreciation and understanding of science by the general public.
Repeatedly, Renn and his children make romantic choices as ill advised as they are understandable.
But they are understandable for a player who has been a Rangers mainstay since the 1989 playoffs.
For all of the persistent doubts about Lin — and they are understandable, given his short résumé — his final statistics are more than respectable.
There is also a need to simplify and standardise the reporting of genomic test results so they are understandable by all healthcare professionals and patients, she adds.
The Dalai Lama has called the self-immolations an ineffectual form of protest, but has also said they are "understandable" and refuses to condemn them.
Such developments are not inevitable - despite being imprisoned by a racist state Nelson Mandela still managed to lead the creation of a non-racial democracy - but they are understandable.
