Nah, you just don't know how to analyse and read it. It's didactic narratives designed to make sense to the reader - not all historically based.
A lot of it is based around literacy and explorations and adaptations of literary forms, jungh vidhya, bir raas, social issues, just governance.
In effect, by doing so, are you categorically agreeing with Professor Piara Singh Padam's viewpoint?
Furthermore, are you also asserting that our Guru Sahibaan were Hindu Kings in their previous lives who divided up the actual GurGaddi of the future in a business deal (when they were Hindu Kings previously) as stated in Bachitar Natak (as opposed to Bibek Buddhi)?
Bachitar Natak states that Guru Sahib had a caste that they were proud of. 1699 destroyed the very concept of caste via Kul Naash.
So which exactly is it? As Vaisakhi 1699 and Bachitar Natak are mutually exclusive. One cannot be both pro-caste and anti-caste.
I totally disagree. Dasam Granth is different from SGGS ji for sure, with a heavier focus on social matters, literature, psychology, language, politics, culture, Indic mythology etc. etc. Repurposing traditional narratives to suit contemporary Sikh needs has also been done.
If Guru ji used narratives to explain things to Sikhs, it's on you to try and grasp the underlying themes and points of the narratives, not discard them because your own preconceptions and mental conditioning go against this.