Hi Alex
I have the following remarks:
- the LGB 26270 is a cog wheel locomotive with a smoke unit that is pulsated by a wheel sensor. The manual even says that because of high currents there is a possibility to disconnect it
- each LokSound XL output maximum current is 500 mA so check with a multimeter or with your CS3 what is the current increase when turning ON the smoke unit. Chances are it is welle below 500 mA.
- you must pay attention to keep the pulsating effect (as originally designed) as the smoke unit may NOT be good for continuous operation.
- ESU decoder, similar to Märklin ones may have the smoke modulation for a given output (Mars lights, blinking, smoke, Telex) but I dont know which CV needs attention

Note: in HO, Märklin pulsating smoke unit current is approx 100 mA

I hope this helps
Jean