Charlotte is a French name, and the CH is pronounced as it is done in France. So therefore you have scuppered your own argument wrt Sorcha by your example.
You could, by your reasoning here, call Charlotte 'CHarlotte', as in char lady, cha cha cha, etc.
'And really this 'it is disrespectful to the language' argument is not really relevant is it?'
It is relevant, really. You can't decide for yourself how to pronounce words in a language you know nothing about. That is not 'language evolving'. It is 'getting it wrong'. To do so despite knowing what the correct version is is to show a lack of interest in and respect for the language. Your DD is going to meet people whose language you have corrupted, people who have named their British DDs Sorcha who have taken care to get the pronunciation right just as many British people have named children Liam, Seán, Niamh, Siobhán over the years and got over themselves and pronounced the names as they should be pronounced. Insisting on pronouncing those names Lyam, Seen or See-an, Nyam or Nee-am, or See-ob-han would be ridiculous. It would be 'getting it wrong', not evolving any language.
Sorcha is based on a word, just as Isla is. It means bright. It is the opposite of dorcha (it even rhymes), which means, yes you've guessed it, dark. There are girls' names based on the same dichotomy -- Soireann and Doireann. Pronounced Sir-inn and Dir-inn (they rhyme too).
'Ice-la is ridiculous (i know people in glasshouses and all that...) but it sounds horrible and doesn't make sense.... and the real pronunciation is much nicer and more elegant' Everything you've just said here could equally be applied to Sorcha. "Sorsha is ridiculous... it sounds horrible and it doesn't make sense.... and the real pronunciation is much nicer and more elegant".
Colleen is a transliteration of the word cailÃn, meaning 'girl'. Another example of taking ignorance to a whole new level.