I can't answer your questions, as ST is not easy to understand. So, you could simplify your ST, transfer all PARAM nodes, and exclude the "bus" node using ABAP.
Program:
types : begin of ty_ls_param, paramname TYPE string, paramvalue TYPE string, end of ty_ls_param. data lt_params TYPE TABLE OF ty_ls_param. data string type string. concatenate '<?xml version="1.0" encoding="UTF-16"?>' '<PARAMS>' ' <PARAM name="Name">GPS Antenna' ' <PARAM name="Status">Connected' ' <PARAM name="bus">test bus' '</PARAMS>' into string. try. call transformation ztest source xml string result data = lt_params. data lx_root type ref to cx_root. catch cx_root into lx_root. endtry.
DELETE lt_params WHERE paramname = 'bus'. BREAK-POINT.
Transformation "ztest":
<?sap.transform simple?>
<tt:transform xmlns:tt="http://www.sap.com/transformation-templates"><tt:root name="DATA"/>
<tt:template>
<PARAMS>
<tt:loop ref="DATA">
<PARAM>
<tt:attribute name="name" value-ref="PARAMNAME"/>
<tt:d-cond><bus><tt:skip/></bus></tt:d-cond>
<tt:value ref="PARAMVALUE"/>
</PARAM>
</tt:loop>
</PARAMS>
</tt:template></tt:transform>