Issues with accessibility in vaadin application

Hi,
I am pretty new to Vaadin. So seeking some help/inputs regarding accessibility in vaadin.  I understand that vaadin claims to be 508 standard compliant. 

We have an application in vaadin (version 7.6.8) that comprises of various vaadin server side components like Buttons, textboxes, combo boxes, Grid etc.

I am running into some accessibility violations while testing the app with IBM's Dynamic Assement plugin extension on chrome https://chrome.google.com/webstore/detail/dynamic-assessment-plugin/aahpafpbmmgednbflpalchnlbicaeppi

I use the 508 ruleset in the above extension.

When I test a vaadin demo page (http://demo.vaadin.com/sampler/#ui/grids-and-trees/grid/multi-select) using the above extension, I run into similar accessibility violations.

Here are the violations that I am running into
1) Frames and IFrames must have a non-empty title attribute.
2) Each form control must have associated label. 
3) For a data table (i.e., the table tag does not contain a WAI-ARIA 'presentation' role or 'none' role), identify headers for the table rows and columns.
4) Combine color and descriptive markup to convey information.
5) Frames that contain content that is not HTML may not be accessible.
6) Do not use ::before and ::after pseudo-elements to insert non-decorative content.

Can these violations be handled somehow or are these known limitations or is it a bug?

Thanks
Gaurav