Unlocking Traits
The only alternative is to buy them unlock from the trainers.
How can I unlock some traits if there is no way to know when the connected event start?
Thanks
Use the GW2 wiki shown above to look up any info and/or use google. If it is a world boss event then you can find what its time table is. If not go to the zone and spot where the event occurs and wait for it. Either way it could be a long wait.
Most events are on a 15-20 min timer, just wait around where the event starts.
You’ll eventually get it. You’ll need to actually research into the events that you need.
The troubling ones are the Temple ones, you can only hope that no one defends the temples, so you can get your trait.