To agree with Amitabh Bachchan English is very Phunny (or funny) language. A language which has greatest number of literature works happening (or happened) has serious scarcity of generalized language rules, e.g. how to spell a sound or how to pronounce a word. There can half a dozen different ways to pronounce one sound. Similarly it has half a dozen different spellings for a word which is pronounced uniquely.
Trouble comes when one needs to write on Indian word in English (karma, nirvana, guru, pundit etc) and otherwise also. I have encountered three names written in three different spellings but pronounced the same. Sandhya , Sandya , Santhya, Santhiya.. Which one is correct? Technically going, none of them. No combination of English alphabet can accommodate these kinds of thousand words (except otherwise UNICODE). Its English, you can spell your name the way you want, where is the problem? Problem is the attitude of “you way of spelling is not correct”.
In one way these differences are very useful, to guess where that is person is from. If a girl writes her name as Sandhya, she is south Indian. If Sandya , she is north Indian. Any “th” ( like “Santhya” or “Santhiya” ) is either from Tamilnadu or Kerala and north-east people don’t name their name daughter as “sandya”. Cool isn’t it ?
Anyways come to the point. To go technically, South Indians pick letters as exactly it sounds in alphabetical chart, north Indians pick it from English words where they are used. For example letter “t” sounds retroflex in alphabetical chart , in English words it can be dental , or retroflex.