I do not have answer and do not rely on striker to score for long time. But I suggest we may try some slightly older striker if we really need a scoring striker.
There was only one real good scoring striker in my teams in last 4 to 5 seasons. He was a ST/AMR corner specialist. But he was much more effective at ST position. When he was in my team, he was about 24 to 27 years old. At that time, he was much older than other players because all other players in that team were below 22. He did not have good performances in first season (no goal in 9 matches). After I start to use him at ST position in next season, he scored a lot and very consistently performed. He was not a slow trainer at his age (he usually got more than 10% with light stretching training in first 2 seasons in my team). Even though he subsequently became a low quality player (about low 4 star before leaving) in the team and played less, he was still among the best scorer in the team. I gave him free kicker role. This should be a reason for his scoring. But he could also score a lot during the match. He can both feet. This can be another factor.