No, openHAB Timers created using createTimer: Actions | openHAB, in Jython see But How Do I…? — openHAB Helper Libraries documentation and for JavaScript you should be able to adapt Experimental Next-Gen Rules Engine Documentation 5 of : Actions (NOTE: that thread was written before there were Helper Libraries and written to show how to create Rules through PaperUI so not everything there may still be accurate).
JavaScript is lazily evaluated. Lots and lots of errors will never appear until the rule actually runs. I would expect to see an error if the trigger where incorrect though.
The big problem when executing the rule from PaperUI is it doesn’t appear to get the scope. Consequently it doesn’t necessarily have access to logInfo, for example. Though you should usually see an error in the logs when that happens.
Maybe you need to enable the logs through. See step 3. at Installation — openHAB Helper Libraries documentation (you might need to click on the JavaScript tab).
$OH_CONF/automation/jsr223/javascript/personal
It’s in the right spot or else you wouldn’t see the “Loading script” log statement and it wouldn’t appear in your Rules menu in PaperUI.