@sun The major problem with SCE: Its entire functionality is based on a custom implementation of the comment form. It does not reuse the standard comment form of WP core.

This means that any potential additions to the regular comment form are inherently lost, and data as well as interactions of other plugins is not accounted for. The Simple Comment Editing plugin forcefully bypasses all of that by introducing custom data structures, custom logic, custom hooks, and a custom presentation.

The consequence is that other plugins, like the recently covered Mollom plugin, are not able to operate as intended, since the underlying operation on the comment entity is hidden away from all other plugins.

I ran a crude test, installing & activating Simple Comment Editing on top of the following collection of previously active comment-ware:

AJAX Edit Comments
Comment Form Message
Comment Hierarchy Adjust
Comments Not Replied To
Comment Notifier
Comment Rating Widget
Comment Rating Field Plugin
Live Comments Preview
MCEComments
Report Comments

After activating SCE, I brought up a Post with hierarchical comments and multiple optional plugin enhancements still displaying, made a new test-comment into the pre-existing hierarchy ... and then edited the new comment using the now-showing Simple Comment Editing icon.

In this admittedly crude test, the other comment-ware continued to look & work as it had, before SCE, and SCE is working alongside them.