I noticed this too, and changed the table to read "si" instead of "ti", because in all the sources I could find on Solresol, "si" was always used. If it should be corrected, then the title of the language should be "Soreso" because we don't use "sol" anymore either - we use "so" instead.  
 Unfortunately the picture can't be changed to say "si" unless someone can use an image editing tool and fix it maybe?