One of the pages on your site(https://www.gdrc.org/oceans/un-seahorse/ocean.html#one) states East Sea as Japan Sea.
This is clearly a mistake that does not respect the on-going disputes between the Republic of Korea and Japan.
To be sure, this is not a territorial dispute because East Sea is obviously the territory of ROK.
But, Japan has been trying to claim this sea as its territory by calling it Sea of Japan despite ample evidence of the opposite.
For one thing, the name "East Sea" appears in the History of the Three Kingdoms in around 59B.C. which is far way earlier than Japanese oldest record on it.
In addition, "East Sea" should be a more reasonable name than "Sea of Japan" for the waters neighbored by many others not just by one country, Japan.
For these reasons and many others that I cannot mention here due to spatial constraints, international laws and regulations including that of UN recommends, "In case of a topographical feature under the sovereignty of more than one country, if countries concerned failed to come to an agreement on a common name, it should be a general rule to accept all of different names in each of the languages used by each of the countries concerned."