For STM32, my view is as follows:
I understand the concern and need for having naming consistency,
thought, I'm concerned about different instances numbering.
Some starts from 0, some starts from 1:
UART_1 in ref manual being referenced as UART_2 in Zephyr
could be source of error.
At least keeping numbering (or "lettering" for A/B/C) consistent from
board/manual to API is required from my point of view.
Then I'm ok if there is a naming convention "UART_x" accross vendors.