You are not going to like my answer, but:I forgot to ask you what is your own version on why Mr. Stone testified the bearing were changing? As you know he stated the same in the affidavit he submitted to his own Captain.
The bottom line is that changes in relative bearings to rockets sent up from Titanic, as well as from Carpathia, were seen from the bridge of Californian that night. Since we know that compass bearings to the rockets should not change by any significant amount, the only valid explanation for the change in relative bearings to those rockets is the swinging of the vessel from which these observations were made. The swinging of Californian may have been somewhat erratic at times, possibly even retrograde, causing a misinterpretation of what was being seen. It also seems that careful correlations in time between relative bearings and ship headings may not have been taken, leading to false conclusions about the movements of the vessel from which those rockets came.