@grishka If you can't help directly, perhaps you can give some pointers.
I'm using GraphViz to generate charts of conversations like this:
https://www.solipsys.co.uk/Chartodon/106063077615765752.svg
That is a chart of (an earlier stage in) this conversation, and highlights the point. Sometimes the chart renders perfectly, and sometimes it doesn't. I can't reproduce the problem, as it's happening on other platforms that I don't use.
If you could glance through that and make any comments I'd be grateful.
TIA
CC: @humanetech