I meant just in terms of line spacing. Remember when we worked at making the Jigsaw pieces work in Lectrote? That was possible only because it was using fixed width formatting across line breaks. If it had used block unicode characters in proportional width font then I don’t think we would’ve written anything to try to detect the blocks and change the line spacing. Yes there may be some exotic characters which display engines could have trouble showing in fixed width, but exotic unicode is always a risk. (I think most CJK characters should be safe, but it depends on the engine and font etc.)
Reverse mode is also available for Glk/Glulx, either through Style_user1/2, or through this extension, which at this moment is supported only in Gargoyle and Windows Glk (though also the WIP Quixe update I shared with you earlier Jeff, though I can’t remember if I fixed the line spacing issue yet or not, I think I didn’t actually, sorry):
Of course these days in Glulx you can also just use images. That might be the most reliable!