Vegan ice cream has chalky texture

I don't make "vegan ice cream" though I do make sorbets that happen to be vegan, most of the time. I found that coconut cream gave me strange texture issues (much harder than it should be based on sugar percentage), "light" coconut cream was better than "normal" in this regard (opposite to what I expected, but I guess it's the fat solidifying), and I think my next coconut batch will be just dried coconut, water, sugar and pectin (my not-so-secret sorbet secret.)

Other than that specific issue, the sugar content of your recipe scans low. Sugar serves an important textural role in frozen desserts, and should be approximately 30g per 100g (30% by weight) for most frozen dessert products. While you'll have some sugar in the fruit, it is not that much, and the agave syrup is partly water, so it's likely contributing only 35g or so of sugar for 50g of syrup.

If you put bananas in any frozen dessert, they'll take over, IME, so I don't find that surprising. And coconut meat has much more coconut flavor than cream of coconut, also IME.

If you wanted coconut raspberry, I'd suggest dried coconut, raspberries (check the sugar per 100g on the package, or look up commercial ones similar to ones you've frozen at home (ie, with or without added sugar when freezing), figure how much sugar you've got from that, add a sugar source to bring it up to 30%, add pectin if you like, and freeze in whatever manner you like. You'll likely need some water, too, though it could all be done with enough raspberries providing their juice to the coconut. I find that a proper mix makes good product whether it's still-frozen or churned.