If you could use it, it would be in a very specific context. The word ‘emotions’ can have a positive and negative connotation. Perhaps you could say: “Happiness is a delightful emotion” or maybe something like: “There are some very delightful emotions that we humans experience.”

I also think "delightful emotions" sounds a tiny bit strange, but not because of any problem of syntax or grammar. I can even understand the meaning perfectly. I guess it sounds strange because I don't think I've heard anyone ever put those words together. But I can think of a possible use case: "This drug causes a range of delightful emotions." Since this phrase came to your mind, but your word choice seems strange to you and me, perhaps you haven't quite hit on the right way to express what you wanted to say. Could you clarify your intended meaning? I like to use the adverb "delightfully". I'm reminded of a character on TV in a particular exchange. Someone was describing a kind of wine he had blended, and he described all the flavor notes in the wine, and she said something like, "how delightfully busy!" thus hiding an insult under a pleasantry. I found that hilarious. In case you aren't familiar with this usage, here "busy" means that something is overly labored, too elaborate, or otherwise has too much going on so that it lacks cohesion and elegance. However, I guess it doesn't qualify as a collocation. That is a rather common construction in English though. At least on TV shows I like and in my social circles, etc. People say, "delightfully" + adjective.

I've had such a delightful morning. I went shopping and discovered a delightful little hidden bookshop. I found it perfectly delightful passing an hour exploring all the various books on the shelves. The owner was very delightful too, as he was so helpful when I asked him questions. I find it most delightful helping you too Anita and I wish you a quite delightful afternoon.

Maybe pleasant emotions? Also I'm a native English speaker and if you ever want to talk you can message me

Delightful would be used to describe the things which "Cause" emotions or "influence" emotions . For instance: 1. the Delightful evening I had with you . 2. the Delightful gift that you gave me