If this plugin understood and interpreted the timesheet.txt back-referencing syntax, we could add a command to jump from a referencing line to the referenced one.

Once #1 is implemented, we could have a command that basically "resolves" the back-reference on a line by inserting the contents of the one we're referring to. Example:

1234  some entry
1345.
1414^

When the cursor is on the 1414 line, invoking this command should result in the following file:

1234  some entry
1345.
1414  some entry

This would be nice for making minor edits to the line or simply to keep your file human-readable.

Note that the resolving would need to be done in a recursive manner:

1234  some entry
1345.
1414^
1520.
1610^

Resolving the 1610 line should of course not result in using the caret character from the 1414 line, but some entry from the 1234 line it ultimately refers to.

Once #1 is implemented, use nvim_buf_set_virtual_text (if available, of course) to display the contents of the referenced line after the one that's referencing it. Maybe this can even be done on each keystroke, so that the user can see while typing whether they are referencing the line they intend to.