Hello,
Your symptoms point to a broken Text Services Framework in your user profile, very typical after an IME install hangs. Try to rebuild your language list so Windows recreates all IME registrations for your account, then make sure the TabletInputService is automatic.
Do this end to end. First uninstall QQ Wubi completely in Settings > Apps > Installed apps, then restart the PC. Next open Windows PowerShell as Administrator and run exactly these commands to rebuild the list. You can add QQ Wubi back later once everything works.
$list = New-WinUserLanguageList "en-US"
$list.Add("zh-CN")
$list.Add("zh-HK")
$list.Add("ja-JP")
Set-WinUserLanguageList $list -Force
Now ensure the IME service is always available and running:
sc config TabletInputService start= auto
net start TabletInputService
Start-Process "C:\Windows\System32\ctfmon.exe"
Sign out and sign back in. The language indicator should be back in the taskbar and switching should work without lag on the desktop. If it does, test typing in Notepad and a browser, then add QQ Wubi again if you still need it.
If anything is still missing after these steps, tell me and I will move you to the next repair step.