In the area of Markovian quantitative modelling, compositional model specification techniques such as Stochastic Process Algebra are widely used. However, exploiting a model's compositional structure for efficient analysis is still a difficult problem and mostly limited to special cases. This paper addresses some important issues in the area of compositional model checking of Markovian models for models with Boucherie-type product form. It closes a long-standing gap concerning the question whether compositional model checking of so-called global time-unbounded Until formulas is possible. The answer to this turns out to be negative. The paper then turns to the area of model repair, i.e. the question of how to fix a model in case it violates a given requirement. Here another general result and a useful proposition for compositional model repair are provided.