Let's take P1907 as an example. Is it accepted into the C++ standard? To which version? When?
Papers can be tracked here.
https://github.com/cplusplus/papers/issues
Entering is:issue P1907
into the search box produces:
P1907 (closed)
and
P1907R1 (merged)
Alternatively,
If you use Slack, you can join the C++ slack at cpplang.slack.com and privately message any paper name to @npaperbot to get information about it.