Bug: Japanese text input fails to convert single-character romaji to kana when a range of text is selected

[12joan]

Description On the Japanese text input, when a range of text is selected, pressing "a", "e", "i", "o" or "u" does not convert this to あ, え, い, お or う. Pressing these keys when the selection is collapsed (i.e. no text is selected) works correctly.

Steps to reproduce

1. Focus the Japanese text input
2. Type "kanji" - it is converted live to かんじ
3. Select か
4. Type "i"
5. The resulting input reads "iんじ"

Demo

https://github.com/user-attachments/assets/c628e4db-9325-4223-9a3f-efe2faadd28b

Expected behaviour The "i" should be converted to an い and the input should read "いんじ".

Additional information I can reproduce this issue on both macOS and iOS. On macOS, I'm using version 1.32.2 (1064).

[zjgoodman]

I can confirm that if you're using a japanese keyboard, this bug does not happen. But I was able to reproduce this as you described when using the built in text replacement keyboard thing