I'm not saying anyone's right or wrong here as there are many ways to accomplish the same thing. It's your 'A'joint, they're your cues and you can build them anyway you want to. This is an opportunity to learn.
The more things you reveal about your construction methods, the more things that get my attention.
I don't use 5-min epoxy for anything except the occasional ferrule replacement where the client drops off the work and wants it back in an hour. I'm not the one in a hurry, the client is. I'll take as much time as I think I can get away with. Generally, the slower the cure of the epoxy, the stronger the bond. 5-min is sufficient for ferrules.
Coco is a tough wood to bond. It has a high 'oil' factor. The 5-min epoxy my not have enough time to migrate into the wood before it starts to cure.
You may find that the epoxy has bonded to your Maple tenon but not nearly as much to the Coco. Pre-washing the Coco just prior to assembly with acetone will help to remove the oils. Some of them anyway.
I can't stress enough, the importance of proper 'A' joint construction. We just had a very informative thread on this topic. That doesn't mean that everyone who reads it will get it right the first time. It's definitely worth a re-read. Get the 'A' joint wrong and the whole cue will be wrong.
Fortunately, you caught it before you went any further.
Take your time.....it's justified.
Maybe it's just me but I never do 2 gluing operations at the same time. IE, I never glue in the connection pin and then immediately make the 'A' joint connection. I want to make sure that each operation is secure in it's own right before I proceed to the next step. By doing all 3 pcs at the same time, connect-pin, handle and forearm, you run the very real risk of not knowing where the buzz is coming from. Is it in the pin? Is it in the handle? Is it in the forearm? Another suspect; is it in the 2 flat mating surfaces of the handle/forearm? Epoxy is notorious for 'wicking' into the end-grain, leaving an insufficient amount for a proper bond.
Again, I really prefer the thinner, slower setting epoxies. This gives me the time I feel is needed to make the handle/forearm connection to my satisfaction. If it takes me 15/20 minutes to make that connection, so be it. It's my time, it's my cue.
I drench the hole and I over-coat the tenon. I WANT to see epoxy squishing out of the gap btwn the two as I'm screwing them together. But here's where it gets tricky. That epoxy is being put under pressure, that's why it's squishing out. It's called hydraulic-action and the pressures can get quite high. So high in fact that you can split the forearm in a heart-beat. That epoxy wants out of there bad and it will find the path of least resistance. If that's through the side-wall of the forearm, it doesn't care. This is where your technique and patience come into play, more importantly your sense of 'feel'. After you've split enough forearms, you'll start tempering your 'feel'. The 'feel' is basically the amount of pressure you sense as you're screwing the handle & forearm together. If you can do this within 20 mins or so, you should be alright.