The author has said that they've redone it since, but the "from-scratch hand-built" framing specifically – for me – somewhat grates given the original heavy lifting from an existing AGPL codebase.
https://github.com/cesanta/elk/issues/75
I want to acknowledge that the original authors don't seem to have minded too much – per that thread – after older versions were dropped.
For context, the current code doesn't look like it is the same shape, the same structure, etc., etc. – it _has_ been rewritten since (the 'since Feb' rewrite mentioned adjacent is related to this, AFAICT).
To the author: I absolutely love what you're doing overall. Keep going! Just be careful, folks.