sorry to hear about your problems with Soylent 1.0. Some people have problems with gas and others don’t, it might help to introduce it slowly into your regular diet. There is also a new 1.1 version being shipped that is supposed to be better for gas.
Regarding your rapid weight gain issues: please be aware that when you are on a low carb diet your body generally stores much less glycogen in your muscles. Each glycogen molecule is surrounded by 6 or more water molecules, so there is a lot of water weight that is lost or added when switching to or from low carb diets. The rapid weight gain you experienced was likely just water from the increased carbs in Soylent. This would all happen the first few days and then level out. You don’t report how many days you tried, but unless you went longer than a week and were seeing weight gains during week 2, I doubt you were seeing anything but changes is stored water.
There are several Keto recipes, just goto the recipe page and search for keto tags, however you are not likely to find anything comparable in taste. Carbs are distinctive and Keto versions don’t have them by definition.
If you just want low carbs, but not all the way to keto then you are welcome to try crude food 1.1, if you don’t add the fruit it is 30% carbs and of course you can always add more protein and oil to lower that ratio further.
Just my experience, but it is hard to make a good tasting Keto version. YMMV