If the cell editor in the QTableWidget is not currently active, typing should normally trigger the editor to start and the key typed will entered into the editor. This is what happens if the US input source is selected for the keyboard.
However, if the either Hiragana or Katakana is selected, the first character typed is lost. Note, if the cell editor is currently active, the character typed will be accepted but if the cell editor is not active the character is lost.
The same phenomena can be also seen when the cell is selected(qtbug96965-cell-selected.png) but not in editing mode.
How to reproduce
1. Use qtbug96965.zip
2. Choose Hiragana or Katakana
3. Start typing あいう ( keybaord, 'a', 'i', 'u')