OK, so i looked up planet and star data on evemaps
The star is a K4V, so its orange-ish, four tenths into the next lower class, luminosity V (dwarf). In essence, a much cooler star than our sun.
Vittenyn II
has an orbit period of 38 days (fine for the star type i guess, mercury for comparison has an orbit period of 87 days)
Density of 6048.79 g/cm³ (higher than earth), and with higher escape velocity and gravity (naturally)
It has however a very low atmospheric pressure (might be a terraformed planet?)
Yet higher mean temperature (309k compared to earth's 288k) probably because of its closeness to the parent star
Vittenyn III
has an orbit period of 68 days (a lot farther out)
Density of 3917.18 g/cm³ (lower than earth), and with lower escape velocity and gravity (naturally)
It has however a very low atmospheric pressure (might be a terraformed planet?)
Yet higher mean temperature, odd (306k almost as high as Vittenyn II), it doesnt have enough atmosphere to actually trap the heat.
The planetary conditions might point towards terraformed planets with large deserts within the tropical zones locked in large landmasses. Moreso in Vitt III than in Vitt II
Cities and human settlement most probably located in what we consider sub-artic/tundra zones, near coastal areas that will smooth season changes, or in narrow valleys between mountain ranges as you move towards the equator (acting as shields against excessive heat).
In the same constellation Trossere, Fricoure and Ainaille also have terran-like planets. So its 4 of 7 systems in the constellation. That could mean a lot in context of how much effort has the Federation invested into terraforming Sinq Laison in general. (as reference Verge Vendor has 33 terran planets Solitude 47, Everyshore 51, Essence 61, Placid 72, and Sinq Laison 110).
Given the above conditions, one could speculate on the major economic actitivies to perform:
Precious stones -> diamonds, rubies, opals, etc. I would discard major mining operations as it would disrupt the terraforming process quite a bit.
Wines - Secluded valleys with the right orientation and dry soils could yield the most exclusive wines in the constellation
Racing - large deserts with no living being could be the best location for extreme racing sports
The rest would be agricultural exports, specially fruits, nuts and various seasoning products.
My best bet would be precious stones, which would give a good indication as to why planet II and III were terraformed, the whole system could have large deposits being a 2nd or 3rd generation star.