I've been watching most of the Laval games, and my answer is that no, I'm not concerned.
Whenever looking at the short term, the process should always be more important than the result. What I'm seeing of Kotkaniemi is that his compete level is high, he's playing well in a lot of different situations, and he's generating offense. Those are the things that matter, that will lead to him re-acquiring his confidence, developing good habits, and becoming a better hockey player.
Though the goals are not coming, he is getting several good shots. That they're not going in is, I'm assuming, a result of statistical fluke, and possibly psychology. He might be nervous to score his first goal, that happens, but once he scores 2 or 3 he'll be fine. The stats page says that he has 25 shots on goal in 11 games. That's not an exceptional number, but a decent one, I don't know if they're accurate in the AHL, or if they're including missed shots. He's gone a little wide of the net a few times.
Right now, the sample is small as Kotkaniemi has played 11 games. However, there are 19 games left in the AHL regular season, plus whatever they play in the playoffs if they make it. So whereas the sample is currently small, it should be intermediate by the end of the season, we'll know better.
Circling back though, I'm just thrilled with his compete level and with his ice time. If he keeps that up and stays healthy through the end of the season, I don't care whether he scores 2,7, or 12 goals in the last 19 games.