I am reading Irène Nemirovsky's novel, Les Biens de Ce Monde. In Chapter 18 Pierre Hardelot is thinking about his relationship with Roland Brugères, his partner in the paper manufacturing business. He thinks
Roland avait pour lui une estime et une amitié curieuses.
That plural ending of the adjective made me do a double-take as I reminded myself that of course it must be plural: it qualifies two curious things. But it leaves me uncomfortable, because they seem more like one admittedly complex qualities. Is this something I should just learn to live with and stop worrying or do French readers raise an eyebrow? Veuillez me pardonner cette question naïve.