bug(mac): output does not appear when using the gff_amharic keyboard for the Firefox browser.

### Describe the bug

It does not produce as " ትአት" instead It shows "ታት"

### Reproduce the bug

Steps to reproduce:

1. Install the Keyman 18.0.238 stable version on macOS.
2. Open the configuration dialog and installed the gff_amharic keyboard.
3. Scenario1:
4. Open the Firefox browser and click in the address bar.
5. Select the "Amharic" keyboard on the toolbar.
6. Type t t, left-arrow, a
7. Verified that It does not produce as " ትአት" instead It shows "ታት"
Scenario2:
9. Open the Firefox browser and Navigate to the "editpad.org" website (Online text editor)
10. Select the "Amharic" keyboard on the toolbar.
11. Type t t, left-arrow, a
12. Verified that It does not produce as " ትአት" instead It shows "ታት"
Scenario 3:
13. Open the Terminal Window.
14. Select the "Amharic" keyboard on the toolbar.
15. Type t t, left-arrow, a
16. Verified that It does not produce as " ትአት" instead It shows "ታት"
Please refer to the attached screenshots



These issue are failed while testing the regression om macOS.

### Expected behavior

_No response_

### Related issues

_No response_

### Keyman apps

- [ ] Keyman for Android
- [ ] Keyman for iPhone and iPad
- [ ] Keyman for Linux
- [x] Keyman for macOS
- [ ] Keyman for Windows
- [ ] Keyman Developer
- [ ] KeymanWeb
- [ ] Other - give details at bottom of form

### Keyman version

18.0.238 stable

### Operating system

macOS Sonoma

### Device

mac mini

### Target application

_No response_

### Browser

_No response_

### Keyboard name

gff_amheric

### Keyboard version

3.1.1

### Language name

_No response_

### Additional context

_No response_