Offloading 50 pax: required by the regulations and Lufthansa wouldn't have had any discretion in the matter. The Cabin Crew members who operated that door bear the responsibility for that one.
Lufthansa personnel disappeared at Lajes: Well I'm guessing that, like just about every other airline crossing the Atlantic, Lufthansa doesn't have any people on the ground in the Azores. Having just landed the crew were most likely told by their Ops to get to a hotel ASAP for rest so that they could be available for duty after min rest. It would have been good
PR if they had been able to hang around with the pax and wave the last one off on the bus but that would have delayed the return back to Frankfurt the following day.
Sounds like keeping the people on board was the correct thing to do. Clear evidence of fire is a no brainer, evacuate. Feel that the cause of smoke might be air conditioning? Well, statistics show that many people are injured during an evacuation down the slides (upper deck on a Jumbo?) and it would be a shame to break people's bones for the sake of a worn out oil seal. A judgement call that the Captain has to make at the time. Sounds to me like he got it right.
On the issue of Lufthansa communications, I was on a LH A320 trying to get out of Frankfurt at the end of a day which had seen snow and then freezing rain. Extremely difficult conditions for the Airport operator and the airlines. For several hours the airfield was closed. The Captain of this particular flight did a superb job of communicating with the passengers. Regular PA's and a wander up and down the forward cabin. We all knew what was going on in the wider world and our place in it. Mind you, his best efforts were snookered in the end when the local authorities refused an extension to the airport opening hours and a couple of thousand pax all began disembarking at once.