My cat reacted to topical flea medicine, washed it off. Is she okay?

You were very smart to wash the medication off Cookie. If you did not use dish soap, I would recommend to rewash the area using dish soap as it is very good at stripping the coat.
While I cannot be 100% positive that everything is ok (as I cannot physically examine her), it's generally a good sign that she has calmed down and is acting more normal. You have two options, take her into the veterinarian or monitor her. If you want to be as safe as possible, you could get her into the veterinarian tonight for an examine as they would be the best ones to determine if there are any neurologic abnormalities or any other causes of concern.
If you choose to monitor her, you need to watch her closely for increased respirations, open mouth breathing (panting like a dog would), stupor, dizziness, trouble walking, seizures, hyper salivating or other abnormalities that involve her central nervous system. If Cookie displays any of the above abnormalities, I would recommend to take her straight away to the veterinarian. Make sure that she is eating and drinking. When in doubt, take her in as its better to be safe than sorry. Go with your gut.
I would not recommend to use this product again on her to be safe. Although reactions can occur with any product, I think Revolution is generally well tolerated and I routinely recommend it. You may also talk to your regular veterinarian about appropriate products to use in your area if you have specific risks like ticks.
I noticed that you listed her weight as 4lbs (which would be very small for an 8month old cat) and the product is labeled for 5lbs. While it may be a typo, make sure to always use the appropriately sized product to decrease the potential for side effects.
I hope this helps and that Cookie recovers normally! Thank you for using Petco Pet Education Center, formerly Petcoach.