Baby’s first piped cake

I like vegan baking but I’ve never really tried to decorate a cake with a real technique (lol). Here is my first piped cake. I decided to make one of the cute 4 inch bento cakes so I didn’t have to make so much frosting. The vegan buttercream melted really quickly so it was hard to pipe and I didn’t make much extra so I didn’t get to practice piping before I just started on the cake lol. If anyone else has a lot of experience with vegan buttercream, please give me any helpful tips! I used the earth balance sticks. I wanted to try the country crock with avocado oil but my store only had the olive oil one and I was worried it’d take too much like olive oil. Thoughts?

The cake is vanilla funfetti with vanilla buttercream.