I installed GTK-G on Win 10 around the same time you asked your other question and likewise I was unable to find mention of creating logs within settings. (My older Mac and MacOS no longer supports GTK-G; a newer library component version within GTK requires a later MacOS.)

Did you check the advanced user settings? Not sure it will give any such extra option.

This is a question worth asking the developer. Unfortunately the dev rarely visits here. At one point the dev said they were unable to access the forum (which might have been the case if using a proxy/vpn unfortunately also used by a previous forum spammer.)
You can still attempt to contact the dev via PM (Private Message) https://www.gnutellaforums.com/gtk-g...tml#post367419 (Right-click their username to see option.)
Otherwise you might need to contact them via Sourceforge. If you do successfully contact them and receive an appropriate answer, could you please reply here. This information might be helpful to other gtkg users.