HB-HOT had a lot of corrosion and fatigue issues and non-conforming repairs, so Ju-Air have their homework cut out for them and hope to be back this summer. D-AQUI was probably in a better state, so I doubt this was the reason, even if learnings from HB-HOT may have prompted a few additional checks and repairs.
It is true that if there was a crash, it would reflect on LH, but I doubt that this was the reason for their decision.
HB-HOT probably got this corrosion while doing a trip to the US and back, at least that is the explanation Ju Air have. The other two have been examined now and found clean according to a comment Ju Air made very recently. The interim report by the Swiss TSB points out that they are not suspecting the corrosion nor what they called irregular repairs to have anything to do with the crash. Local reaction by people who know the inner working of JU Air suggest that the report goes way over the top and simply shows that the investigators have preciously few insight in what it takes to remain a fleet of 80 year old airplanes.
HB-HOY which was stored at Mönchenglattbach is totally free of these issues as it underwent a complete overhaul a few years ago and will be re-activated to replace HB-HOT.
The question whether they will restart operation next spring will depend how much the local authorities will continue their support for this fleet or be scared into submission by their lawyers, fearing retribution. The ressourcefulness of JU Air's leadership should however not be underestimated.
D-AQUI is a very different airplane and has no such issues. However, it was grounded in 2018 due to damage to an engine mount discovered in 2018 during maintenance. It is powered by Pratt and Withney engines.
Currently it appears that most of the previously engaged sponsors are pulling out of such projects, LH just being one. Breitling dropped the Connie and almost all their aviation assetts and it appears they are trying to de-invest themselfs of the aviation image they had (which imho is close to commercial suicide but time will tell). While many folks were saying that the Connie would die if Breitling dropped them, they keep finding new sponsors who keep them going, even though they have massive problems getting it back into the air. I sincerely hope that in Germany there will be enough supporters of D-AQUI to rise money to keep her going. In comparison to the Connie projects e.t.c the JU should be in a much more affordable league financially.