I don't know much about the ropefish since I don't see myself ever having the right setup for one, but I believe they are more or less omnivorous but poor hunters. I'm a little worried about the frog. I believe they are both poor eyesighted and mostly rely on smell to find their food. I don't know if the ropefish would consider the frog a snack or not.
Also, there is the issue of tank height. ADFs require air, so they must make a quick trip to the surface for breath. However, they're like little kids sometimes, they wait until the last second to go for it. I've read in some places that tanks containing ADFs shouldn't be much more than a foot in height since it could cause undue stress on an ADF to swim that far for air.
Of course, that may all be bull-puckey. I imagine they probably live deeper than that in the wild, but maybe not. You might observe the ADF in your new setup to see how he handles the height issue, unless the new and old tanks are of similar height. If he does well, and the ropefish are a good fit as tankmate, I'd consider getting a few more of the frogs to go with your ropefish. It would be a really neat tank to watch.