Another possibility
A technology as advanced as the System's would probably be able to create spaceships smaller than 'Deep Space Vessels' which were capable of reaching Federation territory: they would want to know about potential threats, new technology etc. It would be necessary for suitable cover to be provided to disguise the point of origin of such ships (the equivalent of the Ortega and the Scorpio) and their crews.
Ensor and Avon are both 'inherently highly able with technology' and as I suggested in an earlier email, this might be why they left/were removed from the System if they did come from it - better exile than Alta-zation. Ensor thus has the use of both System and Terran backgrounds to create the tarriel cells - which he does at a much younger age than would otherwise be possible (and he does have the benefits of seeing things from outside). (Probably the same argument could be used with Avon and his development of the teleport system in 'Trial' - he has worked on the Aquitar project).
Orac is developed as a 'jumped up search engine' and computer (and the rumours Servalan mentions in 'Deliverance' probably arise from traces such as are left in 'Traitor' - and being a 'curious computer' persuades Ensor to give him information about the System's computers. If Ensor could get access to his original System-based ship this would not be difficult (perhaps Orac's flyer is a piece of System technology).
(As a possibility in SF generally - would the names of 'most' inhabited planets and their systems be the 'local language' equivalent of 'Earth'/'Home Planet'/'Our Solar System'?)
Jacqui