2dryas:
To load local files through runtime I usually use AJAX's Request URL action and this url form - file:///<path to file>
Without < and > brackets of course! C2 will search it in parent folder (if you write no full path, just filename).
Example:
file:///data.json
file:///data_subfolder/aaa.txt
file:///C:/Users/user/Documents/zzz.log
Note: I check it with NodeWebkit ONLY! I don't know about how it works on other platforms.