It said both On or before and approximately 15 th May 2015 So I...

It said both

On or before and approximately 15 th May 2015

So I suppose, if they delivered a set of accounts on 15 May 2019 , they are all good- as 15 May 2019 would be approximately near 15 May 2015 as it’s in the same century

One has to remember they did engineer the plant infrastructure for a one in ten thousand year event- so accounts six months- one year or two years late would be nothing for such forward planners