@yrannadx

If it is intended (not go back to SIM1, if started withSIM2) then it seems OK.

Let me guess: you do not have PIN code enabled on second SIM, but you do have on SIM1?
In that case the switching to SIM2 occurs immediately after the call release. And a phonet down/up is not necessary (but do not harm either).
So in that/your case just omit down/ups for switch to second SIM and it should work. But it should work also with my approach. What about using command line 'sim-switcher SIM1' in your script (in config file only the switch code)?

So in short:
Never use killall csd, it will create internet (access point) problems.
If there is no PIN code query enabled, switching occurs without any interaction (but it works with my method, too).

-- more edit
I have some extension ready to let my script wait if there is no cell radio connection available. In my case I do need the SIM to be online to successfully switch. Please let me know if that is valid for your adapter too (go into offline mode and dial 002 and see if the SIM switches, I expect not).