You must be sure about maps, i can't tell you exactly what map is active and what every map means, BUT.
Open turbo vanes with 10% (not 10 units). Advance SOI for hot temperature, dont touch for cold temperatures. SOI for hot temperatures should be negative in low-load area and you must put them a little bit after top dead center.
Also another measure is to lower the boost with 10% or ~100 150 mbar from 0 to 15 20 mg, to avoid PID controller to closed turbo vanes automatically more than in n75 map.
Things area clear. To burn efficiently diesel must have AFR in low load from 20 to 35 right?
0 boost means for 1.9 tdi around 480 mg air ok?
AFR lets say 25 : 480 / 25 = 19 mg. Well until 20 mg of fuel you can run with no boost same as SDI cars. they have the best economy, but really no boost is bad for transition to boost , thats why you need to keep a little bit , maybe 0.1 0.2 bar.