Do these concerns also apply in an HTAP or OLAP context e.g. systems like Cloudera's Kudu, which uses Hybrid Time? Or maybe Volt which you also worked on?
I've worked on a system that loaded data into Kudu in near real time and simultaneously ran queries on the data. Kudu has no transactions, consistency is eventual which was sufficient due to our near-real time constraint, however you do need a stable NTP source. We have lost data when the cluster could not get a reliable NTP connection, decided to shut down and tablet servers' data files became corrupted.
Vertica seems to include some of these observations, such as global consistency and group commit. I believe these are easier to achieve (lower overhead) in OLAP due to fewer, larger transactions.
OLAP systems tend to be read only (for analytics) so the question of transactions and consistency isn't really applicable.