bug(mac): backspace a Khmer consonant result in outputs of the vowel before the consonant

[Meng-Heng]

Describe the bug

It seems to only happen on the vowel.

I'm only seeing this issue with Khmer script. The Kenya (BTL) from #10246 works as expected.

Screen.Recording.2026-02-16.at.12.58.27.in.the.afternoon.mov

Reproduce the bug

1. Open Google Sheets --> Double click in an empty cell to type
2. Type s+[+v (This sequence consists of consonant + vowel + consonant)
3. Backspace once to delete the output of v
4. The backspace remove the output of v by replacing it with the output of [.

Expected behavior

It should delete the character, and no output of the letter before it.

Related issues

#14879

Keyman apps

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Keyman version

19.0.198-alpha-test-15561

Operating system

macOS Tahoe v26.2 | Sequoia v15.7.3

Device

Mac Mini M2 | MacBook Pro Intel Chip

Target application

Google Sheets

Browser

Safari v26.2 + v18.6

Keyboard name

Khmer Angkor: https://keyman.com/keyboards/khmer_angkor

Keyboard version

Khmer Angkor v2.4

Language name

Khmer

Additional context

[mcdurdin]

@sgschantz can you triage this please?

Possibly related:

• bug(mac): excess backspace when deleting composed character in Google Docs #10246

[sgschantz]

@Meng-Heng This behaves as expected for me using the most recent build from #15561.
Can you try once again with the latest build from that PR?

I am using Tahoe 26.3, and it worked ok with both Safari and Chrome.