Of course, it is exactly as you say. Icon+g is quite enough. I only gave this “doubling” as an example in case someone doesn’t want to use icon. An icon must be inserted in a special way. I do that with another app. The other characters can be typed normally. 
Short addendum:
I have been able to test this “search system” reasonably well and have not found any errors so far.
I use the metadata label, status and keywords (and sometimes c/mdate). Everything can be combined with everything without any problems.
After a complex search a dynamic collection can be saved. Something that is otherwise not possible at all or only with difficulty … as far as I know