In many regards yes, the system is frame rate dependent
All the logic to determine which sounds are active occur on the main thread, as does the supplying of the audio data to the hardware audio thread. Once the buffer is supplied to the hardware it will play back at the rate that the hardware consumes it regardless of the game thread performance, however, for real time decompression sounds (by default sounds over 5s) the buffers could get starved if you had large enough hitches preventing the double buffer from being filled in time.
Another issue you may run in to is the maximum number of channels. By default we have 64 active channels, which translates to 64 possible active sources. If your sounds are being played often enough and are long enough you will find yourself cutting sounds being cut off or failing to start depending on how the priorities get chosen.
Finally there is also a question of how you’re playing the sounds. If you’re creating a new AudioComponent or just calling PlaySoundAtLocation for each sound, then no issues, but if you’re reusing the same AudioComponent you could again get sounds being cut off before the finished playing.