There is a nice topic on Wanikani here, if you know some that are not listed you should add them ! (It’s a wiki)
I also recommend to check goo and gogen for more cool information about etymology. These are in Japanese so sometimes the explanation are too difficult, but google translate works relatively well.
For example
旨味 : according to goo it’s not a kun+on compound, the mi part is clearly a suffix + ateji (「み」は接尾語)
湖 : according to gogen it’s because originally うみ meant a huge place filled with water (not only the sea), and there was a difference between 塩海, salty umi, the sea, and 水海, fresh umi, lake.