Ah, to be honest this renderer should be deprecated since the new solidify path / extrude modifiers, because it use some special primitives (lines adjacencies) which are not supported by most of modifiers... (Thick Lines should also be redone because of that). I'm not sure we will add new features in tube lines renderer because of that. In theory it's possible to have the same behavior by putting a solidify path and a surface renderer. If not can you expose me your use case may be there is a bug somewhere. The only bugs i'm aware of is the usage of solidify path on 3D mesh which are not supported yet (that's why we leaved tube lines)