Any chance this “Comment.tmPreferences” file (or your version of it) can be included in Sublime, so the toggle_comment command works out of the box with bat files?
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>name</key>
<string>Comment</string>
<key>scope</key>
<string>source.dosbatch</string>
<key>settings</key>
<dict>
<key>shellVariables</key>
<array>
<dict>
<key>name</key>
<string>TM_COMMENT_START</string>
<key>value</key>
<string>:: </string>
</dict>
</array>
</dict>
<key>uuid</key>
<string>C831BAED-BA65-4F98-AE9A-553CE36EF008</string>
</dict>
</plist>