Right. I have not played L5R, only looked at the lore introduction, but from what I gather, it's loosely (note: loosely, about as much as GoT could be said to be based on medieval Europe) on Japan.
But the Three Kingdoms encompass so much more than Japan, and I say the following as a person of direct Japanese descent - to neglect this diversity in history and cultures would not only be ignorant, but also wasteful. There's a rich pool to draw from, and Wyrd has certainly shown to be capable of going deep. The Penangalan is a wonderful reference.
Now to be fair, I am not accusing you of being ignorant. I only heard a rumour, and its verity is unknown to me. What I have noticed is a trend in haphazard naming of characters, with Asian sounding names being willfully chucked together without much thought, which makes me wonder if Wyrd staff were able to name which culture they stem from if asked to do so. This trend continues with the Obsidian Gate and the new master, whose name is Japanese, yet she is the headmistress of an establishment with a Chinese name.
Everything considered, I have great faith in Wyrd, and by extension, in you. You've made a beautiful game, and while it may not have my favourite lore of all time, it nonetheless has a pretty damn interesting premise. Just please, do your research properly. Appreciation musn't become appropriation.