In a small bowl (not your mixing bowl) add the white vinegar, lemon juice, orange and vanilla extracts, and salt together and allow to sit for a couple of minutes so the salt can dissolve. You can prepare the vegan butter and shortening while you are waiting.
Add the vegan butter and shortening to a mixing bowl and allow the butter to soften if it is not yet at room temperature.
Cream the butter and shortening together till fluffy and add in the liquids, powdered sugar, and cornstarch. Start by mixing on low and then high for a few minutes until the powdered sugar is fully incorporated.
Add in the cranberries and mix well.
Frost the cranberry bliss bars and sprinkle the cranberries on top.
Using the microwave, melt the vegan white chocolate in a microwave-safe bowl. Starting at one minute, stir, and then 20 seconds increments for up to one more minute. Stir and check after each 20 seconds, making sure that the white chocolate mixture isn't burning.
Put melted white chocolate into a pastry bag with a small tip and drizzle on top of the frosted bars.
Again, using the parchment to lift, move the frosted bars to a cutting surface. Cut the bars. To get the classic triangle shape, cut the 9x9 cookie bar into three horizontal strips and four vertical strips, giving you 12 rectangles. Cut the rectangles in half from corner to corner.