I'm seeing a lot not liking the use of a Japanese written language on this set due to the origin of the game being Chinese. Genshin Impact is another gacha game with its' primary base being aimed for a "weeby" audience, and not specifically a Chinese audience. With one example I could think off the type of my head was GMK Demon Sword. Based off of Azur Lane another gacha game that originated from a Chinese company, but only one comment was made about it having Hiragana. Most mobile/gacha games are catered to "weebs" and most would associate weeb culture with Japanese culture. I didn't look for more examples but I think this is all based off of preference, and designer like it more "weeby." Additionally, there are quite a few popular Chinese titles like Girls Frontline, Arknights, and Honkai Impact.
But I would have made the Katakana sublegends the base kit considering the "weeb" origins.
I see many weeb sets lately with base latin Alphas which doesn't make much sense to me, except if it's to upsell the weebs on a separate hiragana/katakana alphas set.
Not sure their reasoning to why they didn't decide to have Katakana in base, but I see enough that non-weebs will comment on IC's with remarks like "another weeb set" or "love the color but wish it wasn't a weeb set" or other similar remarks. I had thoughts overall, those interested would pay for the feature versus having people who aren't interested having to buy an additional kit to "fix" the set without sublegends. But this is for times when running a base and an alt alpha versus running two base kits.
Not everyone will be happy with each design choice made, but I like it and the inspiration. I would be fine with either sublegends, but I would like it to be in the base kit. Will be watching and hoping for some nice novelties. GLWIC