As for the main point (support for /t etc.) it's true this is not supported by COBOL, and it would probably be difficult to introduce support at this stage because of compatibility issues.
You can do something like:
Invoke type Console::WriteLine(x"09" & "{0}" & x"09" & "{1}" & x"09" &" {2}", "1", "2", "three");
..or maybe:
78 tab-char value x"09".
... and then:
Invoke type Console::WriteLine(tab-char & "{0}" & tab-char & "{1}" & tab-char &" {2}", "1", "2", "three");
Not very elegant but should do the job...