There is a definite plan in place to re-align/rebuild certain of the taxiways and I believe this came into the public domain on one of the plans at the time of the recent solar farm planning application. I think it is regrettable that there doesn't yet seem to be a timetable for completing that work but I don't see any need to be alarmist about it.
I also don't see that the lack of a 'new' Master Plan is anything to get excited about so soon after such a major redevelopment of SEN as has taken place. A period of operational experience with the new facilities is surely reasonable before rushing into any further development plans. SEN certainly isn't within the category of European airports where A-CDM would be applicable and I doubt it ever will be.
A number of UK airports have taxiways with similar PCNs to SEN with just one or two of 47 or above; NWI for example and those at LCY are 30. At SEN taxiway Alpha is 47 and Bravo & Charlie are rated at 26 and the latter are restricted in their use. I cannot really see a problem with CAA compliance there but perhaps someone who knows otherwise can comment.
I suspect that very few delays are caused by the current situation but it is undesirable going forward as the loss of the use of Alpha for any reason could be embarrassing.