Grating sounds reverberated during an earthquake throughout the town. Did they 'reverberate through the town'? I don't understand the phrase 'an earthquake throughout the town' - the words 'reverberated' and 'throughout' need to be next to each other. And 'throughout' means 'through, and reaching every part''. Be sure that you mean that.
She has a penchant for growing rare flowers in her garden.
A good idea occurred to her as to be used a ploy to decline his invitation. I don't know what the revised version means. I think I understand the original, but 'a good ploy... as to' is odd. 'A good idea as to how...' would make more sense.
He is an apostate of XX political party. I don't think I've met the phrase 'apostate of'. Example: 'He was a lifelong supporter of the Labour party, but became an apostate on 6 May.'
To help those in a predicament is worth being praised.
You don't say, 'to help..is worth being praised'.
Helping those in a predicament is worthy of praise/praiseworthy/ a praiseworthy act.