the last link doesn't seem to point to a file, so I'm not sure if what you write below is already in the document from the first link.
* Maintain and improve the user-facing (frontend) part of our (custom) web applications and (internal and external focused) websites
That's quite a mouthful. I'd rephrase it as
* Maintain and improve the user-facing (frontend) part of our web applications. This includes external and internal applications, and some custom projects.
We then need to update also the next line, "...fixes to the applications we use".
* Collaborate with volunteer contributors around the globe.
=> Collaboration is not a task as such, but a way in which the tasks are achieved..
Yes, but I think it's nice to mention that. We can add it to the section title as "As our future Web Technology Export, you work with a great team of currently twelve, and collaborate with volunteers around the globe to:"
* Take care of tools we use for localisation and of accessibility requirements
The tools are already covered by the "web applications" term. What is meant here, IMHO, is that for all our tools we should ensure proper accessibility as well as localization options, that having a focus on that is a part of the role.
* Make our tools usable both with desktop and mobile devices
=> No idea if that is far reaching, in the sense that it can be very complicated? So maybe add 'as far as reasonable achievable'
We had issues in the past e.g. with the LibOCon website that was not usable from a mobile, so I think this is a key competence the person needs. These days, with devices ranging from desktop to tablet to mobile, at least where sensible we should ask for that. How about "Make as many of our tools usable ... as possible"?
* Follow web technologies and trends and bring them to TDF web services with suggesting, discussing and implementation.
In the current document there is "Suggest, discuss and follow..." - I think that is easier to read thatn "with suggesting, discussing and implementation". We could make it even easier and say "Evaluate web technologies and bring them...".
I propose that Ilmari and me finish the tender based on the latest edits, and aim to publish it early next week.