Fiona, does your daughter have signs of over suppression? Weight gain, not growing well? These would be the key factors in her being on too much hydrocortisone rather than the dose itself.
As Julia says hydrocortisone is synthetic cortisol. I think that cortone acetate and cortef could be slightly different, but not sure exactly what the difference is, or if and how it would effect the dosing, maybe someone can help here?
The most important thing is if your daughter is on the right dose, for what her body needs and as long as she is growing well, weight is normal, good blood test results and she is well in herself.
You could try
http://www.masters-uk.com/medicines/home.php and see if they would ship hydrocortisone to Taiwan, if not they may be able to tell you if there are any other drug companies who would do this, you do need a prescription but they will accept a faxed one from your doctor.
In the UK the smallest dose tablet is a 10 mg tablet which has recently changed and these are hard to cut but the new manufacturers are making steps to change them back to the old shape which are scored and easier to cut.
Best wishes to you and your daughter, Rose