Scripting Tax Schedule Records and Set up Taxes page

Dear NS community,

I am trying to access and update (via suitescript) particular Tax Schedule records (Setup→Accounting→Tax Schedules), and also the "Set up Taxes" page (Setup→Accounting→Set up Taxes).

For the Tax Schedule record, I see that it is not officially scriptable. Nevertheless, I am able to load the record ( record.load({type: "taxschedule",id: 1}) ) and even get some data.

However, when I try update a sublist default tax code (in the nexuses sublist),

using this code ():

var taxSchedRec = record.load({type: "taxschedule",id: 1, isDynamic: true});
taxSchedRec.selectLine({
sublistId: 'nexuses',
line: 3
});
taxSchedRec.setCurrentSublistValue({
sublistId: 'nexuses',
fieldId: 'salestaxcode',