Mixed cook and serve and instant pudding into dessert ingredients but didn't realize until dessert completed. Is it safe to eat uncooked cook and serve pudding?
If you are interested in food safety alone, there is no problem. You might get a bit of a "starchy" or "floury" taste, but not necessarily so. The main ingredients are some kind of starch, sugar or other sweeteners, flavour and possibly some additives. None would pose a problem if eaten raw.
But the real issue is that the texture of your dessert may be off:
The main ingredient in an old-fashioned pudding mix is starch. That starch needs to be heated to gelatinize or, in other words, to thicken the liquid. To achieve good gelatinization, you need to boil the starch for a few minutes. For instant pudding, the starch is pre-treated and often other thickeners are included, so you can skip the cooking step.
Depending in the recipe, using the type of pudding that needs to be cooked instead of instant, will likely result in a more liquid or soft dish. As you don't give the recipe you used, it's hard to say, how much it depends on the pudding for consistency, so you could end up with anything between a total failure and perfectly fine.