Hi Seth,
In terms of “if there is anything you can do” – the likely answer is no. If you were a major investor early on and had substantial voting power or a direct line of communication with the founder, maybe. But especially when investing more passively on Reg CF, Reg A platforms (or through Reg D syndicate), you’re a bit at the mercy of the founder, the company, and the lead/largest investors (if any).
Down rounds and dilution are never easy.
However, it sure beats the alternative – i.e. if the company were to go out of business and your investment went to zero!
So sometimes it’s best to remain positive, continue supporting the company and founder, and hope that this new capital can help them to correct course and get back on a path towards a successful exit.