All I can say about those conditions is dear god, one thing those two will be lacking straight away is Taurine also a ton of antibiotics and wormer can make tummies even worse if they aren't on something to counteract it killing all the good bacteria.
Get some nutrical I would recommend the kitten due to the taurine but you have no time. look for a food that's no grain no filler such as Thrive chicken varieties should be fine and they do a wet and a dry complete selection I've never met a cat turn their nose up at Thrive stuff I would stick to giving the wet kitten for now. Also get some prokolin paste to settle their tummies and put the natural Bacteria back in. Also get some beef and Turkey mince for them and mix it into their food most kittens can eat it raw without an issue otherwise just sear the beef and cook the turkey if you feel better about that. What helps is the blood to encourage them to eat.
What you really need is for them both to eat and lots of it mix in the vitamin paste and the Taurine supplement. At least if they only eat the paste and some food you are getting some calories into them both.
https://fetch.co.uk/protexin-pro-kolin- ... -279190011 Prokolin for the good Bactria and to stop the runny tummy
https://www.amazon.co.uk/TOMLYN-PRODUCT ... s=Nutrical Make sure you buy from an UK based seller who has it in stock. This should be what you use to build them up mix a pea size amount in their food if they won't take it from the the tube.
https://www.amazon.co.uk/dp/B002Y0CETO/ ... +nutri-cal Nutrical kitten to buy for later on as I would keep the on the supplement but you sadly have to wait on US postage for it but the kitten has Taurine which cats need it works out easier to give this instead of the adult cat one so you know they are getting that Taurine if they aren't eating well.
Thrive kitten wet complete food
https://www.amazon.co.uk/Thrive-Percent ... ive+kitten complete wet kitten food so you don't need to worry about a dry with it
Thrive also do great cat treats which are just freeze dried meat and crumbling them over food makes them eat anything usually
Bengals are super susceptible to stress (it's possibly due to the wild blood) they don't always show it but their body usually does so get some Feliway (travel spray and the adaptor plug in)
https://fetch.co.uk/feliway-starter-pac ... -283388011Also I've found that Zylkene mixed into their food works wonders for extreme stress
https://fetch.co.uk/zylkene-20-caps-75mg-229722011Im hoping this should at least stabilise them and get some weight on.
Also love the names I have an Arya myself. Hope you get them both through this.