Not a mistake. In different contexts those words can translate to is. "A river lies in the valley and a dam stands at the end" would be just as good as saying "A river is in the valley and a dam is at the end". Swedish has that same interchangeability, but to a greater degree.
Does Swedish have both present and (I think this is correct) present perfect tenses? To me, it seems that the Swedish word "sitter" can translate to English as either "sits" (present tense) or "is sitting" (present perfect tense). Based on this example, I perceive that Swedish has only one form of present tense verbs. Is this correct?