The lack of access for technical design staff must have been an issue.
I doubt that Basil Read have on their staff people who can specify and design navaids as part of their contract, they will have been just working as installers on something ordered separately. That's what you do in construction with technical equipment specified directly between the client and a specialist, you just programme in for it to be installed, it's known as a "nominated" supplier, ie the client says who it is, and is legally responsible, not the contractor.
It's surprising in a way that there haven't been further flights bringing in technical staff to identify and fix the problems, but I guess even a private charter would not get insurance to somewhere so remote with no navigation kit working. I always thought that as soon as the basic runway was done the rest of the project would be expedited by airfreighting labour and materials in by commercial C-130 from South Africa.