On innovation then refer to the 5 point classification by Imam IzzaDin Abdus Salaam (RehmatUllah Alaih) of Obligatory, unlawful, recommended, offensive and permissible . If you have Reliance of the Traveler, there's a whole section on the subject that will dispell any confusion you may have- W29 from pages 906 onwards. This classification is pretty much accepted by everyone. However, I suspect your question is based on something else and not this traditional accepted categorisation on innovated matters, namely that people are holding khatams to a different standard, then again its not the classification of innovation you look at but people's personal acceptance level of it. In other words are they saying its Fard and mean this literally?