1. You can use the (link-undo:) macro to simulate the side-bar's Undo link
(link-undo: "Undo")
...however there isn't a macro equivalent for the side-bar's Redo link.
2. Depending on how you disabled / hid the side-bar's Undo & Redo links it may be possible to use JavaScript to send a click event to them.
(link: "Undo")[<script>$('tw-sidebar tw-icon.undo:not([style*="hidden"])').click()</script>]
(link: "Redo")[<script>$('tw-sidebar tw-icon.redo:not([style*="hidden"])').click()</script>]
...however there is no easy way to know when an Undo event has occured, which makes it difficult to know when to show your custom Redo link.