You'll want to check your plugin list (via
sm plugins list) and error logs (
addons/sourcemod/logs/errors_*.log). It looks like CW3 may have registered the cvars before it fully finished loading; cvars aren't unregistered if the plugin fails.
Using your files for reproduction, it looks like you've saved the file as
gamedata/tf2attributes.txt, while the plugin expects it to be
gamedata/tf2.attributes.txt (note the first period in the filename). Regardless, you'll probably want to
grab my release of tf2attributes; the upstream releases aren't up to date with the source, so you'll have issues with your copy even after correcting the name of that file.
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