Please use snippets in MX5 and see also: https://forum.mendix.com/questions/5988/Formloader-alternative-Mx5 and https://forum.mendix.com/questions/5813/FormLoader-for-Mendix-5
Some changes within the Dojo version used by mx 5.13 did break the formloader.
So I ported the formloader to work with Mendix 5 in the proper way https://github.com/Andries-Smit/Formloader
Mendix 5 does have snippets. Where ever you can; please use the snippets. In some cases where you do need to edit data in a template grid, you can use the formloader. But before you do; please check if the editable list view is an option too. As a last resort you can fallback on the template grid with this form loader widget.
Please let me know if the formloader is working properly.