In MarkdownEditing, comments of this form are highlighted properly:

[//]: # (This is a comment without a line-break.)

While comments of this form are not:
[//]: # (This is a comment with a line-break.)

Screnshot

I'd like to change this so that the highlighting is not affected by line-breaks.

I used Package Resource Viewer and Color Scheme Editor to try and edit the colour scheme. But, I'm not sure how and what to edit in the .tmTheme xml file.