The error occurs on a line that references S1, where it tries to set the background color of text object 'Text6':
'Text6
Set S1_SlideText = CSlideText(S1.ActiveSlideState.Objects("Text6"))
...
S1_SlideText.BackColor = CColor(c.GetAttrib("color5")
The error message is rather cryptic, but attribute "color5" is probably not defined in the current context. The List object contains "color?" attributes, but they don't contain any value. This often means that the attributes will be initialized using some inline script. However, if you look at the inline scripts, you can see that only color0, color1 and color2 are properly initialized. So, it seems that the original code used more color objects, but only 3 are used in this version (perhaps EP1 ignored this specific error). I think that you can solve it simply by removing the corresponding text objects from S1 (Text4, Text5, Text6) The same holds for S2.