No, filler won't wrinkle, but any edges where you feather down to the plastic- or where the filler is thin - might.
Tech Tip #3441: A couple light coats of Vinyl Wash will likely do the trick. Not etch primer, Vinyl Wash. That horrible green stuff that almost no one uses anymore.
A few years ago I did a new ABS GM front bumper cover for a friend's Buick. Cleaned it several times, till the water sheeted off. Baked it through a full cycle. Cleaned it again, till the water sheeted. Prepped it with a new grey Scotchbrite, and water-based Scuff Stuff. Cleaned it again. Yup, the water sheeted off.
A coat of sealer, base and clear with a flex additive, and it looked brand new.
Installed it and away she went.
Two months later she's back with peeling paint, right down to the bare plastic. No sign of any impact, not even a stone chip. The plastic looked like it had never been prepped.
I stripped it all down to the bare surface, cleaned it repeatedly, gave it two full-wet coats of Vinyl Wash, sealed and painted it. I had no idea if it was going to work, but the last I saw of her, the bumper looked good.
I may as well have paid her to stay away: I lost any profit and was actually in the hole on that F%)!ing bumper.
I've had other painters laugh at me for the problems I had with it, but at least one of those guys has told me since that they've had similar problems with ABS parts.