I have played with the railway diagrams myself but did not find them as suitable for my needs, just inclosing remember there has being many diagraming solutions over the years, search for “diagram tiddlywiki” or diagram at links.tiddlywiki.org other terms include image and visualisations eg ECharts - Bringing amazing visualization tools to TiddlyWiki!
Some dead links will come up but many of these implement diagramming that is separately documented in other open source projects.