The Japanese version is heavily reliant on katakana, even for words that aren't usually written in katakana. This is because, if written in kanji, things have a more definitive meaning. Kanji has meaning, but katakana does not. In this game, you often need to give hints which use words' alternative meanings. To open up your teammates' minds to words meaning something other than their main use, the game design team put most of the words in katakana instead of hiragana or kanji.
This isn't really a plus or a minus, but an important note about your expectations. Code Names is still a fun game.