Commonwealth research was hit in TfW by blockig additiona research slots behind WT and even behind further focuses and full independence. That was compensated by a free faction technology research sharing group to certain extent. Later in MtG the faction technology research was nerfed massively by not adjusting the % values to the new system at all.
Minimum what should be done here is to adjust the bonuses appropriately, i. e.:
Max tech sharing bonus: 100% (from current 50%).
Tech sharing bonus per member already having the tech: 15% (from current 10%).
Upgrading the bonuses from focuses: 10% should be 15%, 20% should be 30% instead etc.