Thanks! It worked! I attach the full script for whoever is interested:
string oldfoldername$;
string newfoldername$;
pe_cd;
pe_dir oname:=folders;
int n = folders.GetNumTokens(CRLF);
for (int i = 1; i <= n; i++)
{
string tmp$ = folders.GetToken(i, CRLF)$;
if (tmp.GetToken(1, ' ')$ == "<Folder>")
{
oldfoldername$ = tmp.GetToken(2, ' ')$; //get the current folder name
oldfoldername$ = ;
}
newfoldername$ = oldfoldername$;
newfoldername.Replace("Folder", "FolderNewName"); // replace "Folder" with "FolderNewName"
newfoldername$ = ;
pe_rename old:=oldfoldername$ newname:=newfoldername$;
}