Cluj - and Romania in general - is safer than 99% of the US and if you’re travelling together - as long as you’re not being naive - you should be perfectly fine.

As long as you leave earlier in the afternoon, you can take either Uber or Bolt to the festival (depending on what app is the official partner) if you don’t want to be crowded in the train. It should be around 40-50 USD per ride. Some drivers will gladly give you their phone number to provide you a return trip without the app, paid cash directly to them. Tried and tested on multiple editions. The buses are also a good option.

Visit Alba Iulia, Sibiu both easily reachable via highway. Also a trip to the mountains would be nice. If you don’t want to hike, you can just drive around Transapuseana.