Recently, Singapore Granado Espada initiated a bot sweep, and banned accounts based on function logs. See [Notice] Botting, Map Restarts and Permanent Suspensions. There are some questions concerning client customization. IAH Staff, Xanxus, clarified the matter thus:
Note that he did not say changing sound files is "legal" with respect to the terms of service. It's probably more like "it doesn't affect servers/players, so we don't really care if you do it discreetly" kind of thing. In any case, doing so won't mark you down as a "bot" as quoted above. If you chooses to do so, you can download selected sound effects files (se.ipf) of other GE clients from 悠轉幻境: Granado Espada, or install and copy/paste from other GE clients.