database/templates/effect.tpl is broken in the release version of the game. See above.
This results in being unable to open effect files in the DBR editor (Unhandled Exception).
Per the above image, this can be resolved manually by deleting the highlighted text. It appears to be a duplication of the cameraShakeAmplitude variable definition outside the scope of any Grouping.
Verified game files and re-extracted to no avail. Also confirmed with another user (on Discord) that this issue is not unique to me.