I think he already signed for Bayern before his euro goal. It was his performance against Bayern that got him signed and most of the Portuguese fans were raving about him. Same thing happened with João Mario, Gaitan, Adrien Silva, Fernando, Malaga etc.
I wouldn't have problem with Bruno Fernandes signing if we already had a good midfield that needed a cherry on the top but we don't and Fernandes doesn't look like a player who dictate the play in the midfield. Moreover, his performance in the Europa League were underwhelming. The Europa team are the kind of team he would meet in the EPL. I have same notion about Barella after watching his individual touches for Italy in one of their games. The intensity was high in that match and he wasn't allowed enough time on the ball and as a result, he was uncomfortable and looked erratic which lay credence to his high amount of poor touches stat. He's likely to meet similar high intensity and physically imposing opposition team in the EPL than in Serie A. Likewise Bruno Fernandes. I admit I haven't seen Bruno fernandes' individual touches but the fact that he was underwhelming in the Europa matches and even in the Serie A is worrying for me. Bast dost scored a lot too, didn't he? The point is I won't rate Fernandes' ability as a midfielder while using his goal scoring attributes as a parameter. He's also the team's defacto set pieces taker.