The requirement for a Graphical UI (GUI) is that the user interacts with it via graphical icons and visual indicators. These can exist within a terminal. So, personally I would say WordGrinder and Finch are GUIs in this literal sense. However, your typical lay user may not interpret it this way.
TUI is a sort of abstract term. Sometimes people mean Text UI and sometimes people mean Terminal UI. I don't think these are mutual exclusive. I would understand a text-only UI to be without any visual indicators, whereas terminal UI could be either text or visual. I guess its also worth noting that the phrase 'TUI' was coined after 'GUI'. Perhaps TUI was coined to differentiate the traditional GUI application (a window drawn on a screen with sliders/buttons) from the traditional terminal application (text-only commands). But nowadays, we have libraries like ncurses, that allow us to draw things within a terminal.
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[0] - Almost; some modes use "graphical" indicators like horizontal lines which are really just decorations. You can mess with them if you try hard enough, but by default they'll be ignored by usual operations like navigation, search or copy/paste.