I've always thought of "architecture" as a high-level description of run-time behavior, not a set of compile-time dependency constraints.
But as I already said in two other comments in this discussion, ProjectReference would be equivalent to what I'm describing in the article, just using language-specific tooling. If you are breaking your solution into various projects and keeping them separate with cross-references among them, you are doing exactly what I was describing already.
so the thing is that a BUILD file doesn't define the build graph, it approximates it -- the build graph is always defined by language-specific tooling and specifications
it's fine that the BUILD file is an approximation! that's as good as you can do, if you want to try to model dep relationships between heterogeneous languages
so when we're talking about the dep graph, "using language-specific tooling" isn't a detail you can brush aside, it's a core requirement for correctness, really