Regarding flying up from the tether and asymmetry. I think I would feel a significant asymmetry in the front lines as they are loaded as I walk the kite back into the power zone. If there was a major snag in the rear to make it fly up you should also feel it as you walk the kite back into the power. Plus you can eyeball the bridle. It is possible, however, to miss a small rear asymmetry because there should be no significant load on the rears.
Having walked the kite into the power, I tuck the bottom tip in a little as I place the kite so it leans forward. I then grab the top bridle and go hand over hand to the top front line. Then with open hand press the front line down and forward into wind as you walk back to the bar in a slight upwind arc. This suppresses any tendency to bounce and nothing much can happen to make the kite fly up. However, in the time it takes to get hooked in a shift can still release the kite into a bouncing but I have never not been able to get things quickly under control by applying rear line tension- usually just a smidge of upper line tension but if the kite is high as I take the bar that may be a smidge of lower rear line tension or both.
Imho bouncing is started by a combination of shape oscillation and gusts/shifts. It is not just inflation pressure but also shape. Some delta shapes with there narrow springy tips making them easy to clamshell are prone to bouncing On landing you can usually get things under control by manipulating the top front line after tethering. However on one occasion in a squall I have had a delta kite which may have lost pressure during the session bounce violently enough to make me hesitate grabbing the front. It was tacoing as it hit the ground and after a few big bounces either a tangle from tacoing or big shift made it fly over to the other side and crash. Interesting I held the bag carabiner bar free to completely sheet out and even though it was a 9m in somewhere around 30knts the pull fully sheeted out did not feel too ridiculous but the wind estimation may well be skewed by how big the bounces were as suggested by knotwindy (local weather station showed gusts of 32knts). I have now added a wichard hook to my sand bag so it is easy to hook the flag ring once chickenloop is on the carabiner to cater for choosing to flag rather than walk up the front line.
We have been getting a silly amount of squalls lately and this has heightened my awareness. Today’s session included shuffling back to the bag after the initial launch to wait out a squall, then 4 more squalls, 3 rainbows, some hail and all on a forecast of easing wind and dry weather.
Luckily the swell period was in the region of 16s and so big flats. I spent much of the afternoon doubled over arse and kite just off the water edging as hard as I could waiting for this forecast drop in the wind. Tethering was the easy bit!!