Provided they survive the transfer they'll be better off in your tank for now than a 30 litre tank. But not for long.
How did you put them in your tank, just take them out of the biorb and put them straight in? Do your parents have the same water supply as you? And I also need to ask, how well do your parents maintain their biorb?
If you put the loaches straight in and the biorb's water is different from your tank, the loaches will be shocked. The water could be different because your tapwater is different from your parents' or if they don't manitain the biorb very well, it could be suffering from old tank syndrome resulting in the water in there being quite different from the water supply, and your tank. (Or dare I ask, maybe it's your tank that is suffering from old tank syndrome while the biorb isn't).
Since they are now in your tank, whatever the cause of their behaviour, all you can do is keep your fingers crossed. For future reference, it is always a good idea to acclimate fish slowly when being put into a new tank, whether it's from a shop tank or someone else's tank to yours.
Of course you may have acclimated them slowly in which case the behaviour is something else, no idea what.
Some shops will sell you anything with little regard to whether it's suitable or not. Sad but true.