I am not Romanian, but my Romanian boyfriend explained to me that the use of acolo in that manner would provide emphasis that the five houses are *there* (and not here, for example). As a general rule, he told me to drop acolo in such a sentence unless really needed for clarity's sake.

Sper ca am inteles cu exactitate ce ai zis. I was about to write in romanian what is next. :)) So... I think you should mention a certain context whith the tow sentences. Both are sound correct if you say them this way. I guess, when you wrote "Acolo sunt cinci case", you were thinking at "There are five houses". When I started first to learn english I saw this difference. When you, in english, say "there are", we only say "sunt", "exista", without "there", in romanian "acolo". Maybe that's why you were a little confuse. :)