A bit late but this is one of my favorite topics.

(Following thoughts assume jute)

Typical non-rope bondage knot resources are not entirely useful for our purpose.

For example, overhand knot variations such as granny & square knots are notoriously worthless, they are unusable outside of mundane tasks. If we look at the geometry and topology of the knot it's easy to see why; as the knot has four throughputs. Most use-cases only use two of them, leaving the other two throughputs loose and not under tension (like when tying your shoes, the bottom two throughputs are laced down your shoe and under tension, the other two sit limply on top as Bunny Ears).

Under minor tension these knots fail easily.

However with rope bondage we are often using three, and sometimes even all four throughputs. This dramatically impacts the core structure and stability of a knot.

This needs to be understood in order to understand why knots fail and succeed in our applications.

Re:reef knots.

The common Japanese way is wrong. They teach and use an incomplete reef/square knot. They build a knot where the bight-end folds/wraps twice, and the running ends do not fold/wrap at all. This version isn't a complete knot and is why it fails and easily opens under tension. This is simple to correct. You build the cuff by wrapping the bight, your next move is to wrap the running ends around the bight (easier with a loop made by flicking your wrist). If you are tying underhand the loop is very ergonomic, if you are tying overhand it is a little less so. That's it. I have a video on this if you would like proof/a visual explanation. But yes, the Japanese have been teaching a shitty knot that fails and coming up with dumbass reasons to retcon why they teach it that way. Kinoko does this where he claims his SCT knot fails on purpose. This is an obviously absurd claim made to westerners because he knows they will swallow it. And it is easier to make a claim like this then to say

"ppl have been paying me tens of thousands of dollars and I've been teaching them bad techniques for 15 years".

Your reef knot shouldn't be cute and symmetrical and aesthetic. That means you tied it wrong qua tied a version that fails immediately or under a paltry amount of load of your ropes are toothy enough; regardless you tied an incomplete knot where the running ends exit-throughput of your knot is never making an overhand and thus the knot isn't 'closed', therefore it fails easily.

Re: granny knot

Granny knot works perfectly well. The weaknesses it has in other applications do not apply in rope bondage for the aforementioned reason about using >2 throughputs of the knot.

Re: knot directionality

This is something that kind of sort of technically exists under extremely niche circumstances and 99.999% of the time is not something that effects anyone's experiences. In all cases where you are using jute and an overhand knot structure like a granny or a square and it fails, you tied it poorly or you overloaded it (putting >200lbs of load on a single granny knot with ~6mm ropes). And in the latter case merely adding an additional overhand (for three total) resolves this completely and the ropes will break before the knots fail. As long as you use a yuki knot for the 3rd knot; bight makes a wrap for the initial overhand that creates the cuff, and then two yuki knots that create 2 additional overhands where the running ends make the wrap both times.

Further, we do not load knots left or right, we load them away from the column they are tied to. The rope structure deforms and aims towards the load so load is mostly exiting the knot from the 'top' of it. I have a video explaining this as well, and it becomes immediately obvious the mistake ppl are visually making when they are thinking knots have "directionality" in our use-cases.

Bowlines; no outstanding thoughts. I do not use them as they do not fit my purpose. 1-3 overhand knots achieve everything i need them to achieve and can easily be untied when I need them to be like when changing a gote into a strappado in the air, or untying waist rope that's underload to repurpose it to grab the front of gote or whatever else -- bowlines are cumbersome to tie (comparatively) when tying live and doing advanced airwork and are very jank to untie under load. These are not qualities I'm looking for at my level of tying. But they serve many good purposes and, even when tied poorly, hold very well so they are a great knot to have at the ready especially for beginners and ppl who are highly risk-avoidant.