This thread will cover everything related to the Japanese translation (typos, wrong/bad translations etc.)
Firstly, let me say thank you for your hard and continuous developing activity! I do love BTT very much!!
I tried to use new UI in Japanese. I felt the almost translation was high level, but also I felt some difficulty to understand in some parts. Some of them are not just related to translation but I would like to share my impression with you. If you cannot understand my English comments, I hope you to ask me. (^^)
- 定期的なアップデートを確認してください(=Please check periodic update.): 通常版の更新を確認する is close to the original English. (Is this intentional change?)
- x本指修正: This should be x本指固定 or x本の指を固定. (修正 is Fix as a synonym of Correction but it does not mean holding or something like that.)
(Trackpad gesture configuration)
- ベーシック設定/高度: How about to use 基本設定/高度な設定? ベーシック is a loan (adj.) word and 基本 is a Japanese native (noun) word. 高度 just means Advanced so I did not understand what is advanced.
- ジェスチャーが有効になりました(Gesture is enabled.): What does this mean? "Enable gesture"? If so, it's ジェスチャーを有効化 in Japanese.
- タッチしながら割り当てられたアクションをリピート: I recommend to use タッチ中はアクションをリピート(=Repeat the action whilst touching) to shorten the text. (I found other too-long texts, especially in Action.)
- リピート率(Repeat rate): Does this mean repeat speed? I like リピート速度 more. (macOS uses キーのリピート(=Repeat of Key) with some tick labels to express it.)
- リピート遅延: Is this recognition delay of repeating? I propose リピート認識遅延 though this is probably not enough to understand... (macOS uses リピート入力認識までの時間(=Time for repeating input recognition. Not good Japanese for understanding.))
- Trigger(トリガー) makes me confused because it sometimes means Gesture(ジェスチャー) but also it is used like as Activation(作動). In addition, I'm afraid many people are not so familiar with this "technical" term, except for engineer, programmer, etc.
- I propose to use 動作(native) instead of アクション(loan), because it's easier to recognise, quicker to read, and shorter. Basically, they have same meaning. (Although, アクション is one of the most common loan words in Japan.)
BTW, I saw slightly too much loan words in the UI than other apps. Using "loan" word is not translation because the big difference is just character even though many loan words are already common. I know l10n is one of the most tough works but I'm also afraid it could be a "wall" for many Japanese to use BTT.
I cannot use my time for contribution so much but maybe I can support you if no native Japanese speaker supports you and you want. ^^)b