It's all in your technique!
Beyond just loving and using fluid acrylics, I have some interesting techniques when it comes to painting my own collage papers. I don't just paint them solid colors, I spatter, I dry brush, and I monoprint, to name a few.
Above is a photo of my workspace, I have a table in my studio on which I have a piece of plexiglass covered in a trash bag. I found out the hard way that if I let the painted paper dry directly on the plexi, it sticks! So now I know I have to let it dry on the trashbag if I need to let it dry indoors, then I can peel it off successfully. This time around, I just took them off the plexi and right out on to the grass so they could dry in the sun. That works best.
I start with Japanese Washi paper (white rice paper, very absorbent) and art store papers. The art store papers offer textures and a variety of thickness. I also often buy art papers with some printing on them (and or glitter in them) that will show through the fluid acrylic application and offers nice texture. I also paint Connor's old workbook pages and book pages from old library books and used book stores.
The sheet of paper above is an example of the blotting technique. This is white Washi paper that I purchased on a roll. I tear off a sheet and keep it on hand to "blot" the excess drips and globs of paint from the trashbag between painting other sheets! Let nothing go to waste, I say. I can also enhance the blotting feeling of this paper by spattering some paint directly on to the trashbag and then blotting the Washi into it. Not only does this technique clean your work surface by sucking up all the leftover paint (remember, very absorbent?) it also makes for some wonderful collage paper when you get the color combinations right!
PS, that wrinkled look you are seeing, is the texture of the trashbag transferred into the paint, a happy accident!