I've often been disappointed by the Phrases section of BWS. Often, I had wished to find idioms there and only had an empty section. Perhaps my expectation that "phrases" should include "idioms" was not that of those who developed this section and the data that populates it. Be it as it may, my suggestion is to use the LN index (and, if it exists, an equivalent OT resource) to have "Idioms" show in BWS (in a section of its own):
Poor translation or misunderstanding can often be the result of not being aware that a particular phrase is idiomatic. So word studies would be enhanced by providing this information.