If you check post 58 ubinfo -a definitely has only one i. Either way, I tried it anyway with the same result.
root@ER605:~# ubiinfo -a -ash: ubiinfo: not found
Ubinfo, in fact all of mtd-utils doesn't appear to be included. (At least not in any of the usual locations or elsewhere in PATH)
/sbin/mtd is the closest I've been able to find.
Base OS says it's Barrier Breaker, so https://openwrt.org/releases/14.07/notes-14.07
(Assuming UBI was something that was in use back then), I could try copying a period/release appropriate version of ubinfo (all the mtd-utils?) over and see if it runs.
(looks like I'd start at https://github.com/openwrt/openwrt/tree/master/tools/mtd-utils)
Honestly, I was wondering if it was enabled as well? Post 41 does show that the V2 was also on Barrier Breaker but on my V1.6 when I hunt around for /dev/ubi0 (what post 52 asks to dump) using WinSCP it does not appear to exist. (Honestly, I really don't know what I'm looking for so maybe that's referring to something else or /dev/ubi0 can't be viewed this way)
Good news!!! One step foward for V2.
does this mean we can flash the sysupgrade file from the TP-Link GUI ?
I'm not sure, maybe @kolya can tell us something about
In my case I'll wait to be fully ported/added before flashing it.
Until someone can reverse engineer the TP-Link firmware file format (layout and magic numbers etc) the only way to flash this is thru UART booting into the initramfs and flashing thru that.
No, as Darbness is saying: at this time OpenWRT cannot build firmware file 'compatible' with proprietary FW format. So at best factory FW will not accept that file. At worst it will 'flash the wrong thing'.