Greetings again Matthias,
I am not sure as to how much Christadelphian literature that you are familiar with or how much you can easily access if you wanted to. You may not be particularly interested. There is a great deal of fairly recent publications, on many subjects, and also a large number of magazines, UK, US, Canada, Australia. For example, I like the four volume expositions of The Psalms, with many different brethren contributing with one or more of the Psalms. There is now a thorough exposition of chapters 1-23 of Isaiah, and there is anticipated two more volumes. John Allfree wrote a number of booklets, but he also did a thorough exposition of Ezekiel 1-39. I like many of John Carter’s expositions, for example Romans, Galatians, Ephesians, Hebrews and some specific articles from when he was editor of the Christadelphian Magazine.
The major foundations of the Christadelphian beliefs were laid by John Thomas in his Herald Magazines of the 1840s, then Elpis Israel about 1850, and then his second Herald series of Magazines from 1851-1859, and then his Three (now published as Five) Volume Exposition of the Apocalypse. Robert Roberts carried don the consolidation of our teaching, covering many subjects, and responding to many slight and large problems. Many of the early Christadelphians had different church backgrounds and may have carried over a few of these ideas.
One area covered relevant to your post is a series of articles by A.Andews called “Sin: its origin, effects, etc.” These articles give a thorough exposition of all aspects of the subject, and the portion in The Christadelphian magazine for September 1876 pages 410-421 gives a thorough exposition of Romans 8:3 and Hebrews 2:14, highlighting the Representative nature of the Atonement, and some rebuttal of the Substitutionary view. The Christadelphian (originally Ambassador) Magazine Volumes 1-24 have now been reprinted, while all the Magazines are available electronically, from 1864-2000 running under Logos Bible Software, and from 2001 to the present as PDFs. A large amount of other literature is also available to run under Logos Bible Software (aka Libronix).
Kind regards
Trevor