FastReport Format function results in Unicode error

I use fastreport 5.4.6 on Delphi 10.2 but fastreport has error when display Format function with Unicode args. Here is error

Create memo with text = [Format('%s' , ['nghìn tỷ'])] nghìn tỷ

It will display "nghìn t? nghìn tỷ"

How to fix it?

Edit

I change function VariantToVarRec in fs_itools.pas of fastreport

procedure VariantToVarRec(v: Variant; var ar: TVarRecArray);
var
...
      varOleStr, varString:
        begin
//          ar[i].VType := vtString;
//          New(ar[i].VString);
//{$IFDEF Delphi12}
//          ar[i].VString^ := AnsiString(v[i]);
//{$ELSE}
//          ar[i].VString^ := v[i];
//{$ENDIF}
          ar[i].VType := vtUnicodeString;
          ar[i].VString := pointer(UnicodeString(v[i]));

       end;
{$IFDEF Delphi12}
      varUString:
        begin
          ar[i].VType := vtUnicodeString;
          New(ar[i].VUnicodeString);
          PUnicodeString(ar[i].VUnicodeString)^ := v[i];
        end;
{$ENDIF}
...
end;

After change

[Format('%s' , ['một nghìn tỷ'])]

will display "một nghìn tỷ". I don't know what will happen if I change function to that (I am a beginner at Delphi).

Fixed. FR 5.6.2 works OK. fs_isysrtti.pas from 5.6.2:

function FormatV(const Fmt: String; Args: Variant): String;
var
  ar: TVarRecArray;
  sPtrList: TList;
begin
  VariantToVarRec(Args, ar, sPtrList);
  Result := Format(Fmt, ar);
  ClearVarRec(ar, sPtrList);
end;

fs_itools.pas from 5.6.2:

    procedure VariantToVarRec(v: Variant; var ar: TVarRecArray; var sPtrList: Tlist);
    procedure ClearVarRec(var ar: TVarRecArray; var sPtrList: TList);
        ...
    procedure VariantToVarRec(v: Variant; var ar: TVarRecArray; var sPtrList: TList);
    var
      i: Integer;
    {$IFDEF Delphi12}
      pWStr: PWideString;
    {$ELSE}
      pAStr: PAnsiString;
    {$ENDIF}
    begin
      SetLength(ar, VarArrayHighBound(v, 1) + 1);

      sPtrList := TList.Create;
      for i := 0 to VarArrayHighBound(v, 1) do
    ...
                    varString:
                    begin
                      ar[i].VType := vtString;
                      New(ar[i].VString);
            {$IFDEF Delphi12}
                      ar[i].VString^ := AnsiString(v[i]);
            {$ELSE}
                      ar[i].VString^ := v[i];
            {$ENDIF}
                    end;
                  varOleStr:
                    begin
            {$IFDEF Delphi12}
                      ar[i].VType := vtWideString;
                      New(pWStr);
                      sPtrList.Add(pWStr);
                      pWStr^ := WideString(v[i]);
                      ar[i].VWideString := PWideString(pWStr^);
            {$ELSE}
                      ar[i].VType := vtAnsiString;
                      //New(ar[i].VAnsiString);
                      New(pAStr);
                      sPtrList.Add(pAStr);
                      pAStr^ := AnsiString(v[i]);
                      ar[i].VAnsiString := PAnsiString(pAStr^);
            {$ENDIF}
                    end;
            {$IFDEF Delphi12}
                  varUString:
                    begin
                      ar[i].VType := vtUnicodeString;
                      New(ar[i].VUnicodeString);
                      PUnicodeString(ar[i].VUnicodeString)^ := v[i];
                    end;
            {$ENDIF}
                  varVariant:
                    begin
                      ar[i].VType := vtVariant;
                      New(ar[i].VVariant);
                      ar[i].VVariant^ := v[i];
                    end;
                end;
    ...

procedure ClearVarRec(var ar: TVarRecArray; var sPtrList: TList);
var
  i: Integer;
begin
  for i := 0 to Length(ar) - 1 do
    if ar[i].VType in [vtExtended, vtString, vtVariant {$IFDEF Delphi6}, vtInt64 {$ENDIF}] then
      Dispose(ar[i].VExtended);
  for i := 0 to sPtrList.Count - 1 do
    Dispose(sPtrList[i]);
  sPtrList.Free;
  Finalize(ar);
end;