Here is a pretty good breakdown of potassium fatty acids:
http://npic.orst.edu/factsheets/psfatech.pdf
In summary, potassium salts can cause irritation. However, the acids generally have a half life of one day and pretty much look like they degrade after a couple of days. So, you might be ok. However, I think bbrock has a good point about figuring out what the insect is or what the root problem is. You may be killing off perfectly natural beneficial insects that aren't the cause of your plants' problems. Just spraying pesticides everywhere indiscriminately killing off whatever insects come in contact with the chemical might not be the best solution. What if the real problem is something eating the roots, or overly moist soil, or bad soil pH? Even the link above says that these insecticides vary in their effectiveness depending on the type of insect.
Finally, if you really want to make sure, I would contact the manufacturer and get and MSDS or some more detailed EPA product literature about the inactive ingredients. The rules about what to list on consumer labels provides a fair amount of latitude and there very well might be something in there that could be toxic to frogs but not required for labeling.
I think taking the time to get more information might be worth while. In the case of the fatty acids it looks like they break down naturally. However, that might not be the case with the other ingredients and you can't always just "flush" everything out of the system, especially with something as porous and with as much surface area as soil. Ever seen a site cleanup for contaminated soil? They don't just flush it. They take away a whole lot of soil and incinerate it.
Either way, please keep us posted.
Marcos