Edina Szöcsik and Christina Zuber have conducted an expert survey on party positions on ethnonationalism (full data are available).
I wondered whether the positions captured in the EPAC were so different from what other expert surveys cover. This figure is a simple scatterplot matrix comparing dimensions in EPAC with two dimensions in CHES (Chapel Hill). 
I only include the dimensions that correlate highly, but what is striking is that such high correlations can be observed.
The dimensions are: ethnonationalism (“ethno” from EPAC), cultural autonomy (“cul” from EPAC), territorial autonomy (“ter” from EPAC), rights for ethnic minorities (from CHES), and political decentralization to regions/localities (from CHES).
I did a quick factor analysis, and it seems that these five dimensions are sufficiently summarized in a single factor (p=0.0129; compared to p=0.159 for two factors).
Didier Ruedin 