It's not that we can't do anything but rather putting your best foot forward. Blocking and processing this at the software level would take valuable resources away from your server for a userbase you may not be serving/catering to. If you have no reason to cater to Russian traffic, why not block it at the network level and not even have them reach your server?
With regards to spam in general, there are pretty heavy spam attacks going on right now. The suggestions if you are experiencing this in countries you do cater to would be to:
Switch to hCAPTCHA, if you're not already using it and ensure you configure hCAPTCHA's "Passing Threshold" to "Difficult"
Ensure you have capable Question/Answer Challenges in place that are not easy for a bot/human to pass but are easy for your audience to pass.
Ensure you do mark any spammers which do get through with the "Flag as Spammer" functionality. This will tell our Spam Defense system that this is a spammer and you can use that functionality to automatically hide or delete their content if you choose to.
If you do want to block IP addresses in the software from registering/logging in, you can do this in ACP -> Members -> Ban Filters. However, it is highly more efficient to do this at the server/network level.
Keep in mind that the Spam Defense system is a learning system and any Spam Prevention plan is not 100% effective. If you are being hit by a new spam attack, unfortunately, there is little we can do about that. However, the above should hopefully put up a good barrier that will slow them down.
There are improvements to spam prevention which are being talked about internally as we do acknowledge there is a lot going on as of late but it is not just our software which has noticed this.