PR #3852 fixes the pattern matching issue for Get-Help. However, the implementation should be using WildcardPattern instead of directly using regular expression. Basically it should use the same code as in https://github.com/PowerShell/PowerShell/blob/master/src/System.Management.Automation/engine/CommandCompletion/CompletionCompleters.cs#L5957-L5969, which implements Directory.GetFiles(path, pattern); in a case-insensitive way,