Can you add option for full wide label? It would be great ability split custom field by the group.
custom-field-label-1-------------------------------------------------------
custom-field-1 custom-field-3
custom-field-2 custom-field-4
custom-field-label-2-------------------------------------------------------
custom-field-5 custom-field-6

Kindly do update the code for redmine 5+

ActionView::Template::Error (undefined method `custom_field_name_tag_bold' for #<#Class:0x00005608d103bf58:0x00005608d03e9638>
Did you mean? custom_field_name_tag):
9: <% split_on = (custom_field_values.size / 2.0).ceil - 1 %>
10: <% custom_field_values.each do |value| %>
11: <% if value.custom_field.field_format == 'label'%>
12:

<%= custom_field_name_tag_bold(value.custom_field) %>

<%= custom_field_tag_with_label :issue, value, :required => @issue.required_attribute?(value.custom_field_id) %>