I come up an idea to make filter blocks by keyword.

1. Save the file at download link at documents\Trackmania\Scripts\EditorPlugins
2. Enable at MapEditor Plugins-view by clicking it active.
3. Press Ctrl-F at the same time to popup filter blocks the map.

For example: Road, Wall, Ice... Plugin will match any part, and it's case-sensitive.

Known issues: entering Grass will select all the ground blocks as well as they are part of the map.