How can I remove craft acrylic paint that has been mixed with silicone oil from multiple surfaces?
If the spill has already dried it would be easiest to use a putty knife and scrap off as much as possible (for all surfaces). There will probably be some residual paint left, but by removing some through scraping it will be easier to clean with a fluid.
Once the scraping is done use a cleaning fluid such as lacquer thinner on the porcelain and tile surfaces. They won't be affected by the solvent. Use a bristle brush or terri-cloth to rub the spot away.
To clean the fiberglass surface try this product:
Finally for the painted wall surface it may be simpler to touch-up paint the the spilled spots after lightly sanding them. If not you'll have to use a solvent such as the lacquer or Goo-Gone. This will dull the paint surface so unless it won't be noticeable you may end up painting anyway.