If the client is made into different jars for different Minecraft version , I came up with an idea to make switching between it more convenient .
Save all the different version of .jars in specific location . Example : .minecraft > Liquidbounce - MultiVersion > B73 > 1.8.9.jar , 1.12.2.jar .....
Then , create a Liquidbounce version selector (.jar & .json ) that is able to launch in Minecraft Launcher
It will then show a simple UI for user to select which version they wanted and loaded from the folder in 1)
New button is added in Liquidbounce main menu so it can trigger the version selector again . This makes user able to switch version quickly without reselect it in Minecraft launcher .
But if something like ViaFabric / MultiConnect is added into client itself , all these thing can be avoided and makes user switching between version more seamlessly .