In your Bstation you need to store the status of which playback had been requested using a variable.
For example you can choose to use the variable 1, if you press the button 1 of the Bstation to start the playback 1 of the LPU then you set the variable 1 to 1. If you press button 2, then variable 1 goes to 2. (when everything is off, variable goes to 0)
Create a variable actionlist, and create an action for each value of the variable.
One action will be, when variable 1=1 then send an OSC message that will update the status of the corresponding button in kiosc touch.
Do the same for when variable 1= 2 to 6.
Last step is to create an OSC action triggered when the tag of the first page is received. In this action create a variable task and select refresh variable 1.
The refresh will make the Bstation send again the messages corresponding at the variable value.
To make it even better, the best would be to send the message to the LPU when the button of the bstation is pressed, set the variable depending on the feedback message received by the LPU. This way you are sure that the connection is working, and then send the OSC feedback message from the Bstation using the variable value to the Kiosc Touch.
I hope this is clear enough!
Good luck
