I don't like the idea that you are changing tiles. First of all the trees dont at all work together with houses. You should probably keep using FR styled tiles and maybe just add some custom ones or the ones from RSE. Your mapping is quite good though you should probably try a bit more gamefreak's styled mapping if you will be keep using FR tiles becuase that is where FR tiles truly shine out! Other than that, I'll look forward for more updates because it seems like a really good hack so far!