What would be good alternatives that could replace the word "unacceptable?"

Native speaker’s answer
Rebecca
In this context, I'd suggest saying something like "horrendous," "disgraceful," or "terrible," since he's emphasizing that the kingdom is in bad condition. But other words to use instead of "unacceptable" are "unsuitable," "insufferable," or "inadequate." Which could all work well here too. Ex: The dish you made was unsuitable to serve. Ex: She said my outfit was horrendous and that I needed to change immediately.