If they're in the 34l then asking if the fish are compatible is the least of your worries right now. That tank is extremely overstocked and some of the fish are going to grow far too big for that tank aswell as not being kept in the correct numbers.
Polka dot loach - Grows to 5" n should be kept in a group of 3 or more
Hill stream loach - As mentioned it likes cool fast flowing water (Bettas are the exact opposite)
Xray Tetras - I personally wouldn't have them in a 34l, it depends on dimensions but it just doesn't seem quite big enough full stop... either ways it's not that bad and it is more of a personal preference than a 'If you leave them in there they'll get ill'.
Female Betta - Shouldn't be a problem with any tetras, short finned bettas are normally fine (male or female).
I really would get your stocking levels sorted, if you re-homed/upgraded the loaches to tanks more suitable to them then you 'might' be ok stocking wise. But it'd still be very heavily stocked and need very regular and very good maintenance.