Answer
Despite the fact that setting this testcase is described in the Sterling-LWB/LWB5 certification guide, neither of the two modules support 40MHz wider channels in the 2.4GHz band.
Please disregard that test case on page 13 in Sterling-LWB/LWB5 certification guide version 1.2 or older.
Only 20MHz channels are supported in the 2.4GHz band by these two modules.