Can I add rose water to this recipe?

Ashleep -
Because rosewater and vanilla are both floral essences or extracts, I would be cautious about using them together. I think the flavors would fight each other, and neither come through clearly.
Probably the rose flavor would work better in the chocolate muffins. In that case, omit the vanilla from the recipe and use a VERY small amount of rosewater - say, 1/4 to 1/2 tsp for the total recipe.
Here are a few tips for planning - a general article on using rosewater from Epicurious, a recipe for using a rosewater frosting on vanilla cupcakes (so maybe the flavors would be complementary and not fight), and a recipe from Ottolenghi and Goh for a flourless chocolate cake with a rosewater frosting.
If these recipes aren't to your taste, have a look around at writers or sites you trust.
https://www.epicurious.com/ingredients/how-to-cook-with-rose-water-article#:~:text=Instead%20of%20vanilla%2C%20swap%20in,%2C%20are%20gluten%2Dfree).
https://www.sprinklebakes.com/2012/02/vanilla-rosewater-cupcakes-for-modcloth.html
http://herestheveg.blogspot.com/2020/06/flourless-chocolate-layer-cake-with.html