Scientists say early and impressive statistical reports linked forcing kids to write right-handed to stuttering and other language issues.
Today, research in this area has died. Few talk about it at all.
We know little more on this question than in the 1930s” because studies since then “have ignored the question of hand training and have focused on the broader question of whether speech disorders are more common in left-handers generally.
Source:
https://www.press.jhu.edu/newsroom/stuttering-and-retraining-left-handed-children-mid-century-us