Roblox is still hiring! Feel free to reach out (or reply here with contact info) if you'd be interested in working on the developer/creator-facing side of the company. We do ML/NLP, APIs, cloud services, real-time collaboration tools, and more.
Good question! Not sure. I can find out for you on Tuesday (feel free to email me at rfrankel@roblox.com to remind me). We do hire senior ICs remotely in the US (IC5+, ~=L6+ in Google terms); if we do hire remotely in Canada, it is probably with a similar bar. And we have a Vancouver office, if you happen to be in that part of the country.