Well, hard to see how there were able to come to the conclusion of "fundamental issues" etc without even visiting the factories or flying the solutions proposed:
The fundamental issues has nothing to do with the factories. What the factories do is tell you how well/efficient you can put the plane together. Factory visit would not make sense either way because the plan is to set up a mod facility in the UK anyway. Besides, the E-7 do not have a current factory to be compared.
There was already rumbling that the Israeli proposal would have been too small for the UK needs (smaller radar and lack of space for battle space management needs). The Swedish proposal would have plenty of space, but has other issues as mentioned above (both acquisition and development).
The one thing about the E-7 is you can train the crew the RAAF while the plane is being mod so you do not loose months getting up to speed with your own frame.