Hebrews 10:11-12 (KJV) 11 And every priest standeth daily ministering and offering oftentimes the same sacrifices, which can never take away sins: 12 But this man, after he had offered one sacrifice for sins for ever, sat down on the right hand of God;
I am aware that this word ordering and punctuation is consistent throughout almost all of the English translations. The comma after 'for ever' is the key. However there are some translations in different languages which have got a somewhat different word ordering and punctuation, thus making the 'for ever' a description of how He sat down.
The whole point is that He did NOT sit down forever but rather offer one sacrifice forever, and I believe this is a doctrinal truth.
So my question is: Mainly to those who are more familiar with how the Greek grammar works. Is the original text of Hebrews 10:12 clear of how the passage is meant to be understood? Also, if a brief explanation is possible that would be great.