I find it lacks some easy way to do alignments or grouping, which makes editing frustrating. Could be a good language re-design opportunity.

yes and that led me to a more fundamental question : is it even possible for an easy way to do fine grained adjustments. The finer granularity brings complexity. that makes it unreadable (especially for the untrained) and hence set aside and forgotten. The other way is to narrow down and focus on a well defined subset of problems.

either way the number of people willing or compelled to learn it will be tiny. and it hence becomes a niche, perfect for a long-term side project but with no real return.

my conclusion was to stop looking and use D3 or custom code ( good looking charts for humans).

this project is trying to do the same, balance verbosity in text with granularity in the charts with a narrowish usecase : agent consumption.

That's the best option for now. But it can also be frustrating to ask AI to do small edits on D3 just to fix some idioms (like switching order etc) and they kept messing up with other stuff accidentally. Thus I still believe have a language with native representation for these diagram concepts would be helpful.

Good news is that AI do make new language a bit more accessible than before! If your agents can use it well and you can steer easily, it will naturally be good adoption.