but here goes another one, which i think should be working in 23lt.
(defun c:mirror_text_height (/ text_bb point_1 point_2 insertion_point)
(foreach text (vl-remove-if 'listp (mapcar 'cadr (ssnamex (ssget '((0 . "text"))))))
(setq text_bb (textbox (entget text))
point_1 (mapcar '+ (setq insertion_point (cdr (assoc 10 (entget text))))
(mapcar '* '(0.5 0.5) (mapcar '- (cadr text_bb) (car text_bb)))
)
point_1 (polar insertion_point
(+ (angle insertion_point point_1) (cdr (assoc 50 (entget text))))
(distance insertion_point point_1)
)
point_2 (polar point_1 (cdr (assoc 50 (entget text))) 1)
)
(vla-mirror (vlax-ename->vla-object text)
(vlax-3d-point point_1)
(vlax-3d-point point_2)
)
(entdel text)
)
(princ)
)