I personally think "Maximise conversion" is the best when starting out this gives Google the opportunity to bid aggressively in order to get you conversions.
I usually don't go for Target CPA because of the bottlenecks you highlighted.
I only attempt tCpa when I have enough conversion data.
If the document is authentic, it offers a rare glimpse into how major capital raises often work. Private placements are commonly used to attract large investors before a public offering, and such investors may receive terms that differ from what is later available to the wider market.
However...