I don't think these are possible yet in Radian Studio?
Pretty much everything is possible. More precisely the question is whether a particular capability you seek is provided as a pre-built command.
That's not just a spinning logic for the sake of spinning logic distinction, either... it's a practical distinction in a system where, ideally, a limited number of well-formed commands and capabilities can be recombined in limitless ways to achieve any desire.
So asking, "is it possible" can result in a "sure... do this" in a description that involves just one step with one command, or, perhaps, a couple of steps with different commands, and so on until at some point there is a sequence of moves that is pretty lengthy and may be clear to an expert but which isn't possible for most.
Within that gray area between one-click-wonders and a paragraph of SQL only Tim and Adam understand, is where one must draw the line between "dedicated, canned command" and "this is the magic of recombining a limited number of general commands..."
In the case above, here is one thought experiment way to create a one-sided buffer is a) draw the full buffer on the line you want and put it aside. b) Now, draw a slightly bigger buffer on the same line. c) Extend the last segments of the line at both ends to some distance greater than the bigger buffer distance, you now have a line that extends beyond the boundaries of that bigger buffer. d) Use that longer line to split the bigger buffer into two parts and delete the part on the side you don't want. e) Intersect the remaining half with the original buffer in a) above, and that is your one-sided buffer. Sounds long but it probably could be written as a very compact SQL expression.
You could do the same with all of the other canned forms of buffers (capped ends, etc.) one encounters in, say, Arc.
Whether it makes sense to do those as one-step, dedicated commands in Radian or in 9 is entirely up to a mix of initial engineering based upon Suggestions received to date (read the Suggestions page to see how the process works) and then as modified thereafter by future Suggestions. I haven't specifically searched that database of suggestions but off the top of my head in 20 years I don't think I've ever seen a suggestion recommending capped end buffers or one sided buffers, so I doubt that will bubble up in priority. It could be one reason such suggestiosn aren't there is that with Release 8 such things are very easy to do with simple combinations of existing, interactive editing commands.
To get deeper insight and lookahead on what is planned, join the process as 9 starts rolling out. That will be very soon now and in a way that will be even easier to join and participate than the beta process for Radian.