hello. first, let me state i didn't much have any issue with downloading, installing and playing the game through MSStore.
HOWEVER, one thing i have observed is what appears to be this... the MSStore is serving us NA related assets. and the launcher is downloading the base Japanese client plus patch/update data.
to me it seems like this is not the right order to do it... Windows is treating the game as a modded app, but it is treating the data downloaded through launcher as the modded data. problem is there, i think. we should be downloading the base Japanese client from the store, and the launcher would download the NA assets and patch/update data.
just a thought!
at any rate, i do understand the gripes. there is good reasons it has been 2 years since last touching MSStore for anything -_^ MSStore is indeed known to cause issues, but i think maybe is possible this not a MSStore issue. at least, not entirely.
as for the lobby lag issue. this is seems totally unrelated to the MSStore. appears to have something to do with the launcher.
again, just a thought.
most likely an unrelated issue... [spoiler] the only issue i personally encountered was with Gaming Services. trying to launch the game simply took me to the MSStore page for Gaming Services, which was already installed. a quick uninstall and re-install fixed it, but only temporarily. uninstall, restart pc and reinstall, same. uninstall, restart, reinstall, restart again... same, the fix was only temporary. i had to uninstall, restart PC and delete a folder for Gaming Services somewhere in WindowsApps. reinstall and reboot again for good measure. [/spoiler] bold end