I've had issues getting either Guerilla or Kornman2 to open up certain model_animations tags, specifically ones located under cinematics\animations.

I can specifically confirm an issue opening tag cinematics\animations\cortana\level_specific\b40.model_animations. On opening the tag, the program immediately closes and gives no specific error message in the debug.txt file;

03.22.14 23:38:11  guerilla pc 01.00.00.0609 ----------------------------------------------
03.22.14 23:38:11  reference function: _write_to_error_file
03.22.14 23:38:11  reference address: 4011a4
03.22.14 23:38:11  Couldn't read map file './guerillabeta.map'

The tags were extracted using the most recent version of HEK+, and I am able to open and adjust other model_animations tags without issue, also having been extracted with the same program. Is this a known issue? Should I try to find a different tag extractor, or will it not make much of a difference?

Does the animation play in-game?
The tag maybe corrupted. Sometimes extracting tags break things.
Try this!
http://hce.halomaps.org/index.cfm?fid=6690
This is what I used recently to fix most issues regarding extraction.
Thank you Delicon20.

Thats all I know sorry.