Those are exactly right. !
In case non-EFI boot, if you install Haiku to USB thumbdrive or USB attached external drive, it matters which USB port you use to install and boot from, especially if you have more devices plugged in at boot time.
Generally you can install Haiku onto drives in any USB port, and boot from those drives plugged in any ports - especially if the drive is a thumbdrives or flashdrive in USB external case, without a motor, that would need a higher voltage too.
Previously - till USB 2.0 - there were ports provided these higher volts specified, but not all ports, so it was exactly named which port capable to attach an external HDD with one cable,
so then there were Y-type cables to attach such USB 2.0 cases - using 2 ports, instead one, to have enough voltage to spin the motor too, if there were no such ports in the machine.
Besides not all ports was connected to USB hubs with several speed, so there were separated by speed as well. So it mattered which port you used in case Haiku install.
Not just becase the speed of the access, but the several USB versions’ support status in Haiku. For example interestingly USB 3.0 and USB 2.0 services were differently regarding input devices, storage devices, or miscellanous devices. Especially nowadays when you can plug a cheaper USB 2.0 drive (that’s often cheaper due to the USB version, not the quality or capacity of the drive itself) and a more expensive 3.0 or 3.1/3.2 thumbdrives, and the port connected to both EHCI and XHCI hubs internally. In case Beta4 I had to switch from Sandisk to Samsung big capacity thumbdrives, as Samsung has a better fallback support to USB 2.0, that seemed that needed in case storage in case Beta4. On the Sandisk drive I had Haiku BFS corruption issues, meanwhile there were no yet memory errors (then) by the laptop system diagnostic. It had put an end with the Samsung FIT drives with the same 256 GB as the Sandisk had which was stricktly USB 3.0/3.1 drive - it seems. As general BFS drive now works for me as a backup archive drive, with USB A and USB C connector - flawlessly.
Haiku had not tolerated if I put another port when it was plugged during install - sometimes stalled at booting, I do not remember at which icon .. sometimes even none lit up.
In case legacy boot, if I just relied on to boot order to boot from USB storage device, then it had mattered in which port it was plugged in .. as BIOS wanted to find for boot device first in a specific port, and there were plugged in another USB storage device without any bootable drive (if not partitioned) or partition, then do not skipped that drive or partittion and went to the next, but immediately reported to not found any bootable partiton. THIS IS BIOS stuff NOT Haiku.
Of course, Haiku bootloader also can report that cannot find bootable partition, that’s another issue to resolve. I described potential issues before the bootloader run at all. Sometimes the Haiku already installed, just the partitioning issue should resolved, or a Bootman install would help to boot the Haiku - selecting the appropriate from many partitions, or the UEFI should be reconfigured, or created a ESP partition for it at all, and put the bootloader file(s) there. This way many possibilities can be that block the boot the Installed Haiku or boot the USB installer drive at all.