The define for split->str in gnc:strify in report-utilities.scm reverses the 3rd and 4th parameters (monetary values), and so presents the amount as a value and vice-versa. specifically in rows 1085 and 1090 the xaccSplitGetAmount and XaccSplitGetValue need to exchanged.
Ah you mean the format-string does not match amount/value and should be "Split<d:~a,acc:~a,val:~a,amt:~a>" instead. Good catch. Will fix tonight. This gnc:strify function is really a development tool and should probably be moved somewhere else appropriate.
in maint https://github.com/Gnucash/gnucash/commit/c7c76c2e for 3.8 onwards