function GetPositionOf(LineNr, ColNr: Longint): Longint;
is not there anymore.
You can use CPLineNr to move to a certain line if that helps.
There are also some functions in TWPRtfDataBlock (WPRichText.ActiveText for example),
{:: This function calculates numbers which can later be used with ParagraphFind } procedure GetParagraphNr(par: TParagraph; var FirstLevelNr, SecondLevelNr, ChildNr: Integer);
{This function counts the characters from the begining of the text until the provided paragraph and then adds the povided position. If the paragraph was not found the Result value = -1. Note: all paragraphs care counted as CharCount + 1 for the Carriage Return. Please note that tables and table rows also add 1 to the sum - although they are not visible }
function GetPosition(par: TParagraph; posinpar: Integer): Integer;
{:: This function calculates a paragraph reference for a certain position. If the position was not found the last paragraph is returned }
function SetPosition(pos: Integer; var PosInPar: Integer): TParagraph;