One small tip for a date validation check and convert into text with month text:

1. using function module ‘DATE_CHECK_PLAUSIBILITY’ to check if it’s the valid date;
2. get month texts from table t247 with a language key then concatenate.

*---------------------------------------------------------------------*
*       FORM format_data_with_text                                    *
*---------------------------------------------------------------------*
FORM format_data_with_text USING    ip_date
                           CHANGING op_text.
  DATA: lv_stext(3),
        lv_date LIKE sy-datum,
        lv_fcmnr TYPE fcmnr,
        lv_suffix(2).

  lv_date = ip_date+0(8).
  CALL FUNCTION 'DATE_CHECK_PLAUSIBILITY'
    EXPORTING
      date                      = lv_date
    EXCEPTIONS
      plausibility_check_failed = 1
      OTHERS                    = 2.

  IF sy-subrc <> 0.
    op_text = ip_date.
  ELSE.
    CASE lv_date+7(1).
      WHEN '1'.
        lv_suffix = 'st'.
      WHEN '2'.
        lv_suffix = 'nd'.
      WHEN '3'.
        lv_suffix = 'rd'.
      WHEN OTHERS.
        lv_suffix = 'th'.
    ENDCASE.

    CLEAR: lv_stext.
    lv_fcmnr = lv_date+4(2).
    SELECT SINGLE ltx
      INTO lv_stext
      FROM t247 WHERE spras EQ 'EN'
                    AND mnr EQ lv_fcmnr.

*    CONCATENATE lv_date+6(2) lv_suffix lv_stext lv_date+0(4)
    INTO op_text SEPARATED BY space. " with date suffix 
    CONCATENATE lv_date+6(2) lv_stext lv_date+0(4)
    INTO op_text SEPARATED BY space.
  ENDIF.
ENDFORM.