IME in progress syntax highlight color is wrong in some cases

[kitbdev]

Tested versions

Godot v4.4.beta2 and v4.3.stable
Didn't test other versions

System information

Windows 11 (build 22631) - Multi-window, 1 monitor - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 2070 (NVIDIA; 32.0.15.6614) - Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz (12 threads)

Issue description

When typing in the IME, syntax highlighting uses the wrong color if there is a different colored section after it.
This can affect the color of the text after the IME.

See:

20250204-1854-24.3521280.mp4

After the IME is accepted, it gets updated so it is not a big issue.

Steps to reproduce

1. Have multiple colored regions next to each other, like ("") #
2. Type using the IME

Minimal reproduction project (MRP)

N/A