In the 10.1 release of the framework RDForms most issues was centered on improving validation:
Validation information per field: if a field fails to validate there is now a validation message just below it. The validation message was previously provided only in a datastructure upon validation and implementors could use it to render an error message, e.g. at the end of the form or in a dialog. This was clearly insufficient as put a high burden on the user to localize the problem.
Deprecated values are marked better: Deprecated values are marked similarly as the validation messages, just below the field.
At most, at least and exact one child: Introduces three new attributes (styles) atLeastOneChild, atMostOneChild, exactlyOneChild to indicate the cardinality of how fields are counted together in a group. For example, when providing a dcterms:format you want to provide a dropdown with common values and a complementary a free text field for all other cases. At the samt time you have the requirement to only allow a single value, in this case either the attribute at most or exactly one child is suitable.
Briefly about the RDForms framework:
RDForms matches triples against a template and then provides editing, presentations, and validations by utilizing renderers in different UI frameworks. The actively supported UI frameworks are currently React, Bootstrap, Bootstrap material design and jQuery (the latter only supports presentations). RDForms is used heavily in EntryScape to facilitate a range of different use-cases, i.e. support various metadata profiles.