You don't mention any specific criminal records, but if you go to the online catalogue of the National Records of Scotland (
https://catalogue.nrscotland.gov.uk/nrsonlinecatalogue/search.aspx) and enter the search term Adam Liddell (that spelling!) and select "Phrase", you will get an entry confirming that they have the trial papers: (Click on the blue Reference"and you get the details describing the item).
National Records of Scotland
Reference JC26/1838/216
Title Trial papers relating to John Buchanan, Adam Liddell for the crime of robbery. Tried at High Court, Stirling
Dates 17 Sep 1838
Access status Open
Location On site
Level File
Finding aids 19th Century Solemn Database
Previous numbers JC26/714
Accused John Buchanan, Verdict: Outlawed, Verdict Comments: Outlaw and fugitive, Sentence: Outlawed and put to the horn. Note: Tried with Adam Liddell.
Adam Liddell, Verdict: Guilty, Verdict Comments: Guilty in terms of own confession, Sentence: Transportation - 5 years. Note: Tried with John Buchanan. Pannel cannot write.
You
might be lucky and the papers might give some backgound information about Adam.
We see that he was tried at the High Court in Stirling in September 1838. It is strange that you say he was transported in 1842, and one wonders why there was such a long time between the sentencing and the transportation.
("Pannel" - variant spelling historically of the noun panel, which in Scots law meant (
https://dsl.ac.uk/entry/snd/panel) "A prisoner at the bar of the court, an accused person in a criminal action from the time of his appearance in court"
To "put to the horn" in Scots law in historical usage was to declare a person an outlaw.