"What happened? The firm, Terra Firma, effectively shut down due to poor performance"

This statement does not appear to be factually true - https://www.terrafirma.com/, https://finance.yahoo.com/news/terra-firma-capital-partners-founder-153…

Nothing wrong with IRR vs ROR - one is money weighted and the other one is time weighted/one is better for computing one's personal rate of return as it takes into account specific cash flows and their timing, while the other is better at computing rate of returns that can be used to compare investment performance. Obviously the specific IRR of any investor can be very different from ROR of the investment product he has chosen to put money in. Cordially