Just tried the uninstall method and it worked. So /fonts and ;fc-cache is ideal for updating the default font to a new version.
This time used the default names: Caecilia_LT_65_Medium.ttf, Caecilia_LT_66_Medium_Italic.ttf etc. and it worked
Thanks for this method!
(Click to enlarge)
17:10 is 5.40 from K3/K4 latest patch, 17:16 is the lastest in Touch 5.1.2 - that is v5.00 beta of Caecilia font.