<input type="hidden" name="<inp2:l_FieldModifier field='cust_LinkAddress' type='required' value='1'/>" value="1"/>
<inp2:m_RenderElement name="inp_edit_box" prefix="l" field="cust_LinkAddress" title="lu_fld_LinkAddress"/>
But this tag isn't working at all, when you try to make multilingual custom field required (don't show "*" mark near field name & don't check if it was filled on submit).
For example this has no effect:
<input type="hidden" name="<inp2:l_FieldModifier field='cust_MLField' type='required' value='1'/>" value="1"/>
<inp2:m_RenderElement name="inp_edit_box_ml" prefix="l" field="cust_MLField" title="lu_fld_MLField"/>
Ready for testing.