"I have been speaking Esperanto since the year two thousand."
Translation:Mi parolas Esperanton ekde la jaro du mil.
That would be "I had been speaking Esperanto since the year two thousand (until the period in time that we happen to be talking about now".
You're still speaking Esperanto, right? So the present tense is correct. English uses the present perfect, Esperanto (like e.g. German) the simple present.
If we went by Latin rules, whose perfect tense can act as simple past or present perfect, it would be right.