Power of Ultra Instinct
One very important factor which was mentioned multiple times in the episode was that Goku was fatigued. This was mentioned a lot of times by Champa and including Beerus. This is very likely the writers trying to say that if Goku was at full power, he would've been able to face Kefla. So I think one can't jump to a definite conclusion whether Kefla is stronger than SSJB+Kaioken Goku. The last kick landed on him by Kefla was obviously not as strong as her previous attacks so, in other words, you could assume that Goku was extremely fatigued which resulted in him losing his form All Super Saiyan forms are multipliers to the base form. We know for a fact that the SSJG multiplier is superior to the SSJ3 multiplier and obviously, the SSJB multiplier is a lot higher than the SSJG multiplier(Based on Goku's fights with Jiren and Kefla). The multiplier would remain the same whether Goku is fatigued or not but what would change is his initial base power. The UI transformation is also a power multiplier which also makes him reach a state with complete mastery of self-movement. This is because we see Android 17 remark on how goku managed to overcome the drastic power difference and go toe to toe with Jiren. Also, we see Picollo state how he was growing stronger with every blow. Finally, when Dyspo and Toppo attacked, we know for a fact that full power Toppo is superior to SSJB but UI Goku was easily able to push him back and not just dodge his attack. So it is obvious that even the UI transformation acts like a power multiplier. Lets say Kefla manages to achieve Super Saiyan 3 during the course of battle with UI Goku or if we see Jiren fighting seriously at full power against UI Goku, we can gauge it's power. As of now, we don't exactly know how strong the transformation is.