I don't know how you work that out? I confess I don't know the X50/550 that well but I think it's a basic hourly combined service, operated by two vehicles (hence my slight error on the hourly bit)? I was thinking that you'd want to extend both the X50 and 550 hourly northwards from Aberaeron to Aber?
I similarly must confess to not knowing the route that well now, but I used it regularly a year ago for two years before that and had a pretty good idea what the diagrams were before the 06-plate Tempos (and YJ55BKN) from Arriva arrived.
YJ55BKF's Diagram
05:45 Cardigan - New Quay - Aberystwyth
07:30 Aberystwyth - Cardigan
08:50 Cardigan - Aberaeron
09:35 Aberaeron - Cardigan
11:00 Cardigan - Fishguard - Haverfordwest (412)
13:00 Haverfordwest - Fishguard - Cardigan (412)
14:30 Cardigan - Aberystwyth
16:05 Aberystwyth - Cardigan
18:35 Cardigan - Aberporth - New Quay - Aberystwyth
20:55 Aberystwyth - New Quay - Cardigan
YJ55BKE's Diagram
07:20 Cardigan - Aberystwyth
09:10 Aberystwyth - Cardigan
10:50 Cardigan - Aberaeron
11:55 Aberaeron - Cardigan
12:50 Cardigan - Aberaeron
13:55 Aberaeron - Cardigan
Never worked this bit out, but I think it did local trips eg. Cillgerran and Poppit Sands
17:36 Cardigan - Aberporth - New Quay - Aberystwyth
19:45 Aberystwyth - New Quay - Aberporth - Cardigan
The majority of 550 trips to Synod Inn seemed to be diagramed for ex-First YJ55BJK. The 18:15 Aberystwyth - Cardigan (and the corosponding northbound working) were RB02DAF, but I don't think that'd really be necessary with some slight tinkering to the timetable.
Exact timings may be slightly different now, but from the little I've seen since then, I think the diagrams are the same but with the 06-plates replacing YJ55BKE and YJ55BKF (sadly).
Five buses were fitted with wi-fi for the 412 route. However, if you look at the timetable for that it requires only four vehicles. The 5th wi-fi bus was YJ55BKF, since it ran the 11am Cardigan - Haverfordwest and 1pm return, which has the effect of shifting the four main 412 diagrams along one slot. Running 412 as 4 diagrams would release the Tempo from the 11am Cardigan - Haverfordwest and 1pm return cycle, allowing the X50 to extend to Aberystwyth I would think.
Also, you mention the facilities in Aber that Aberaeron doesn't have, and that this might be some sort of "social justification". Well, the people of Aberaeron and New Quay can already access them by Cymru Express. The people in Cardigan can access those in Carmarthen (BTW, the hospitals in Bangor and Carmarthen are much bigger with a greater range of services and catchment area than Aber) so you're (the WG) basically trying to justify something on the grounds of those people who live in a few villages between Synod Inn and Cardigan.
From Cardigan it can be much faster to use Aberystwyth station than Carmarthen for some destinations though, just as it is probably faster to get to Cardiff from Aberystwyth via the former X40 to Carmarthen than just by rail.