The tooltip for the Multi-Spectrum Sensors, an upgrade for both Tau fleets, is either adding extra information or the effect of the upgrade isn't being properly applied.
The tooltip says that both Escorts and Light Cruisers are affected:
The Emissary and the Merchant are both Light Cruisers and also have 9,000 units of sensor range:
However, in game... the Emissary isn't applying the upgrade, while the Warden Escort is:
Similarly, the Merchant isn't applying the upgrade, while the Orca Escort is:
After all - should Light Cruisers get or not get the extra sensor range?