You are free to modify it but yeah most of them don't put much of a delay on the effects. And the looping is just because they keep updating themselves as renpy calls them. I imagine you're looking to modify the SwapText though and you're free to modify that to how you want it to work. It uses it's swap_to_1 variable to keep track of which character it should be. So probably just need to treat the current timer variable it has to be a delay instead and remove the logic for switching back. Might need to add more code in there too if you want more than just the letter swap. Hopefully that helps though.
Viewing post in Ren'py Kinetic Text Tags comments
Thank you! I did find a slapdash work around, by having two different lines of text, using the wait and no-wait functions {w=} {nw}. One line has a word with the glitch tag, the other has no glitch. When played together, the first line of text appears normal, delayed for a second, then swaps to the next line when it hits the word with the glitch effect.
Makes it look like the text gets deleted and replaced with a brief glitch effect as it happens. It looks exactly like I wanted and It wouldn't have worked without your code! Thank you.