So I came across the answer here. The command:
adb shell "setprop persist.sys.language fr; setprop persist.sys.country CA; setprop ctl.restart zygote"
However after using this command I could no longer change the language with ADB again. I've tried other variations (even back to English to no avail). Such as:
adb shell "setprop persist.sys.language zh; setprop persist.sys.country CN; setprop ctl.restart zygote"
adb shell "setprop persist.sys.language es; setprop persist.sys.country ES; setprop ctl.restart zygote"
adb shell "setprop persist.sys.language en; setprop persist.sys.country US; setprop ctl.restart zygote"
Each command visibly did nothing. What am I missing here?