Transform multiple entries in cell into new columns in R

Question

I have a messy dataset with multiple entries in some cells. The numbers in paranthesis refer to the specific columns "(1)", "(2)", and "(3)". In this example multiple entries in cell 30 refers to column (2) and 20 refers to column (1). No information for column (3). I would like to split up/extract the values in the cells and create 3 additional columns.

Several hundred cells are affected in several columns. Dataset In the end I would like to have 3 new columns for each column affected. Any idea how I do that? I'm still a rookie so help is much appreciated!