I have worked extensively with
@mexxico on this issue. We had 1.4.3 doing a good job. I have just started working my caravans in 1.5 so I don't have a ton of information yet, but from early returns it appears "ok" they do take a good 2-4 weeks game time before investments start returning good profit.
As put by mexxico they are high risk/high reward and mostly shouldn't be used when at war since they do get captured easily. As for non war times I am still in the process to see results of profit and survivability like the video I posted for 1.4.3
If things are not the same I will bring to mexxico's attention to see if he can work on it. He was just finishing a major diplomacy project but I hope to have some numbers to compare to 1.4.3 by this weekend to see how different things are.