I'm not familiar with the autoEQ database, but earlier you said you were trying to use json files for convolution. If you read a little further on the autoeq instruction page, you'll see that the autoeq authors specifically don't advise you to use textual files for convolution. Starting from the part you quoted:
Convolution equalizer is the preferred way to use AutoEq results.
AutoEq supports convolution equalizers with FIR filters as WAV files [...]
To use the FIR filters, download the appropriate WAV file and import it to the EQ software of your choice
[Emphasis added]
They advise you to use the WAV files for convolution, not other files. Looking through the repository, I suspect the text or json files are (based on their naming scheme) probably intended to be entered into a parametric or graphical EQ bank manually or programmatically. But files in a textual format aren't convolution filters (for any convolver I've ever used anyway) and won't work to convolve anything in JRiver.
If you have a look at the JRiver wiki on convolution linked above, it also explains that you need a convolution filter in an audio format such as WAV, APE, etc.
So if you haven't tried using the WAV files from autoeq, that's probably your next step. If you're saying you've tried to use the autoeq WAV files, but JRiver doesn't recognize them as valid convolution filters, that's a different issue. Being more specific about what you've tried and the specific file names and formats would probably be helpful.