This is a good question. No. Not in the final packaged games. Some of its data remains, but the json contents are digested before runtime use.
The json files are loaded in the Unreal Editor, and the information they provide are stored in-memory in parsed structures, so the Editor can have all the information on the current platform's SoundBanks. Whenever you see the Wwise Picker, it actually polls all the information from the WwiseProjectDatabase module, that is a 1:1 in-memory representation of the json themselves.
Then, there is another module, WwiseResourceCooker, that takes the individual information bits from the json files, and creates a binary representation, pre-chewed, of the specified asset. That binary representation is stored in the final .uasset file of your cooked and packaged game (but not the editor uncooked assets). The information itself is very sparse. There are some IDs, file names for the assets stored in Unreal's IO Store, and optional debug name.
This cooked information is what's used to play events and sounds, either in editor, Play-In-Editor, or in the final packaged game.