The brochure states its faster than most ships of its size and it states it has 4 TR2 thrusters. How is that achieved, compared to the constellations TR5 thrusters (according to ship stats) and the way lower weight of the constellation class?

This is a flaw of the current stats page and matrix, and will be remedied with the update coming online with the release of SC Alpha 3.0. The thrusters of both ships will most likely be in the same power band alongside updates to their mass. The current stats page does not support the internal design for a lot of items at present.