The bug you linked to seems rather esoteric (someone didn't want to manually type "import {blah} from package"...?). If you start to type that import, it'll autocomplete the rest for you. And once it's imported, it's very very good at traversing library files and types and bringing you to the definitions (VScode can do this too).
Does it have bugs? I'm sure. And it has its own absurd annoyances (like https://youtrack.jetbrains.com/issue/IJPL-60969/Show-path-in...) that might never get fixed. But in general it works great.
If it's important to you, I guess this is not the right IDE for ya!
Anyway, sorry, I hope they figure it out, but it's not something I've ever had trouble with. If it's an issue for you too, you might wanna write their support or just don't use the IDE.
https://youtrack.jetbrains.com/issue/WEB-31686/Autocomplete-...