You should think of using and import as the “real” ways to track code. includet is deliberately intended to be “track just this file”—it’s designed as the manual alternative to the automated smarts of using and import. You can turn Tvaccine into a package in seconds (GitHub - invenia/PkgTemplates.jl: Create new Julia packages, the easy way) or use push!(LOAD_PATH, dir-of-Tvaccine.jl). Then using Tvaccine should do what you want.
The second issue is a known bug. Since that state of affairs is rather transitory (once you add the file and restart everything works going forward), it’s not really been a priority of mine. For anyone really bugged by this, there was a start on a fix that could use help getting over the line. Unfortunately, the internal architecture of Revise has changed substantially since then so I suspect it’s not a small project.