https://kb.askmonty.org/en/mysqld-options-full-list/ - MariaDB options page that shows the 2-step deadlock variables:
deadlock-search-depth-short is a number for the short search depth for the two-step deadlock detection, deadlock-timeout-long is a number of the long timeout for the two-step deadlock detection, in microseconds, and the deadlock-timeout-short is a number of the long timeout for the two-step deadlock detection, in microseconds
These 4 variables are not used in InnoDB at all, according to serg. There's no documentation on how they're used in Aria. The docs should be more verbose about these options, how the 2-step detection should work, and where it works and doesn't.