As mentioned in Selecting the Active Channel/Trace, if you are using E5071C revision A.9.60 and above, you can select the trace directly by using TRAC{1-16} for all SELected commands. As such, you do not need to make a trace active before assigning a command to it.
The following commands allow you to select the trace directly by using TRAC{1-16}. Note that the active trace is not changed by this command:
SCPI.CALCulate(Ch).TRACe(Tr).BLIMit.DB
SCPI.CALCulate(Ch).TRACe(Tr).BLIMit.DISPlay.MARKer
SCPI.CALCulate(Ch).TRACe(Tr).BLIMit.DISPlay.VALue
SCPI.CALCulate(Ch).TRACe(Tr).BLIMit.FAIL
SCPI.CALCulate(Ch).TRACe(Tr).BLIMit.MAXimum
SCPI.CALCulate(Ch).TRACe(Tr).BLIMit.MINimum
SCPI.CALCulate(Ch).TRACe(Tr).BLIMit.REPort.DATA
SCPI.CALCulate(Ch).TRACe(Tr).BLIMit.STATe
SCPI.CALCulate(Ch).TRACe(Tr).CONVersion.FUNCtion
SCPI.CALCulate(Ch).TRACe(Tr).CONVersion.STATe
SCPI.CALCulate(Ch).TRACe(Tr).CORRection.EDELay.MEDium
SCPI.CALCulate(Ch).TRACe(Tr).CORRection.EDELay.TIME
SCPI.CALCulate(Ch).TRACe(Tr).CORRection.EDELay.WGCutoff
SCPI.CALCulate(Ch).TRACe(Tr).CORRection.OFFSet.PHASe
SCPI.CALCulate(Ch).TRACe(Tr).DATA.FDATa
SCPI.CALCulate(Ch).TRACe(Tr).DATA.FMEMory
SCPI.CALCulate(Ch).TRACe(Tr).DATA.SDATa
SCPI.CALCulate(Ch).TRACe(Tr).DATA.SMEMory
SCPI.CALCulate(Ch).TRACe(Tr).DATA.XAXis
SCPI.CALCulate(Ch).TRACe(Tr).EQUation.STATE
SCPI.CALCulate(Ch).TRACe(Tr).EQUation.TEXT
SCPI.CALCulate(Ch).TRACe(Tr).EQUation.VALid
SCPI.CALCulate(Ch).TRACe(Tr).FILTer.GATE.TIME. CENTer
SCPI.CALCulate(Ch).TRACe(Tr).FILTer.GATE.TIME. SHAPe
SCPI.CALCulate(Ch).TRACe(Tr).FILTer.GATE.TIME. SPAN
SCPI.CALCulate(Ch).TRACe(Tr).FILTer.GATE.TIME. STARt
SCPI.CALCulate(Ch).TRACe(Tr).FILTer.GATE.TIME. STATe
SCPI.CALCulate(Ch).TRACe(Tr).FILTer.GATE.TIME. STOP
SCPI.CALCulate(Ch).TRACe(Tr).FILTer.GATE.TIME. TYPE
SCPI.CALCulate(Ch).TRACe(Tr).FORMat
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.DATA
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.DOMain.COUPle
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.DOMain.STARt
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.DOMain.STATe
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.DOMain.STOP
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.EXECute
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.PEXCursion
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.POINts
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.PPOLarity
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.TARGet
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.TTRansition
SCPI.CALCulate(Ch).TRACe(Tr).FUNCtion.TYPE
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.DATA
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.DISPlay.STATe
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.FAIL
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.OFFSet.AMPLitude
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.OFFSet.MARKer
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.OFFSet.STIMulus
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.REPort.ALL
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.REPort.DATA
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.REPort.POINts
SCPI.CALCulate(Ch).TRACe(Tr).LIMit.STATe
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).ACTivate
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).BWIDth.DATA
SCPI.CALCulate(Ch).TRACe(Tr).MARKer.BWIDth.STATe
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).BWIDth.THReshold
SCPI.CALCulate(Ch).TRACe(Tr).MARKer.COUPle
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).DATA
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).DISCrete
SCPI.CALCulate(Ch).TRACe(Tr).MARKer.FUNCtion.DOMain.COUPle
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.DOMain.MULTiple.RANGe
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.DOMain.MULTiple.STARt
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.DOMain.MULTiple.STATe
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.DOMain.MULTiple.STOP
SCPI.CALCulate(Ch).TRACe(Tr).MARKer.FUNCtion.DOMain.STARt
SCPI.CALCulate(Ch).TRACe(Tr).MARKer.FUNCtion.DOMain.STATe
SCPI.CALCulate(Ch).TRACe(Tr).MARKer.FUNCtion.DOMain.STOP
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.EXECute
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.PEXCursion
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.PPOLarity
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.TARGet
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.TRACking
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.TTRansition
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).FUNCtion.TYPE
SCPI.CALCulate(Ch).TRACe(Tr).MARKer.NOTCh
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).NOTCh.DATA
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).NOTCh.THReshold
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).SET
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).STATe
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).X
SCPI.CALCulate(Ch).TRACe(Tr).MARKer(Mk).Y
SCPI.CALCulate(Ch).TRACe(Tr).MARKer.REFerence.STATe
SCPI.CALCulate(Ch).TRACe(Tr).MATH.FUNCtion
SCPI.CALCulate(Ch).TRACe(Tr).MATH.MEMorize
SCPI.CALCulate(Ch).TRACe(Tr).MIXer.XAXis
SCPI.CALCulate(Ch).TRACe(Tr).MSTatistics.DATA
SCPI.CALCulate(Ch).TRACe(Tr).MSTatistics.STATe
SCPI.CALCulate(Ch).TRACe(Tr).OFFset.XAXis
SCPI.CALCulate(Ch).SELected.PLIMit.DATA
SCPI.CALCulate(Ch).SELected.PLIMit.DISPlay.LINE
SCPI.CALCulate(Ch).SELected.PLIMit.FAIL
SCPI.CALCulate(Ch).SELected.PLIMit.REPort.DATA
SCPI.CALCulate(Ch).SELected.PLIMit.STATe
SCPI.CALCulate(Ch).TRACe(Tr).RLIMit.DATA
SCPI.CALCulate(Ch).TRACe(Tr).RLIMit.DISPlay.LINE
SCPI.CALCulate(Ch).TRACe(Tr).RLIMit.DISPlay.SELect
SCPI.CALCulate(Ch).TRACe(Tr).RLIMit.DISPlay.VALue
SCPI.CALCulate(Ch).TRACe(Tr).RLIMit.FAIL
SCPI.CALCulate(Ch).TRACe(Tr).RLIMit.REPort.DATA
SCPI.CALCulate(Ch).TRACe(Tr).RLIMit.STATe
SCPI.CALCulate(Ch).TRACe(Tr).SMOothing.APERture
SCPI.CALCulate(Ch).TRACe(Tr).SMOothing.STATe
SCPI.CALCulate(Ch).TRACe(Tr).TRANsform.TIME.CENTer
SCPI.CALCulate(Ch).TRACe(Tr).TRANsform.TIME.IMPulse.WIDTh
SCPI.CALCulate(Ch).TRACe(Tr).TRANsform.TIME.KBESsel
SCPI.CALCulate(Ch).TRACe(Tr).TRANsform.TIME.LPFRequency
SCPI.CALCulate(Ch).TRACe(Tr).TRANsform.TIME.SPAN
SCPI.CALCulate(Ch).TRACe(Tr).TRANsform.TIME.STARt
SCPI.CALCulate(Ch).TRACe(Tr).TRANsform.TIME.STATe
SCPI.CALCulate(Ch).TRACe(Tr).TRANsform.TIME.STEP.RTIMe
SCPI.CALCulate(Ch).TRACe(Tr).TRANsform.TIME.STIMulus