Proposed works nearby, at the grid substation that will feed the rail feeder station, were discussed in February in the Borders line decarbonisation thread:
From Midlothian View: https://www.midlothianview.com/news/borders-railway-electrification-bid-revealed/ Borders Railway electrification bid revealed Electrifying plans which would lead to a greener future for part of the rail network in the Borders have been disclosed. Network Rail has...
www.railforums.co.uk
Tweedbank is one of six feeder stations in and around central Scotland that were contracted in 2022. Four of them are adjacent to existing electrified lines (though also relevant to supplying proposed electrifications, including Ferguslie which no doubt helps to supply the completed Barrhead line). The other two, Tweedbank and Thornton, are not adjacent to existing electrified lines. When the financial situation deteriorated, the electrifications could be postponed or slowed down, but the feeder stations were already committed.
Maybe there has been some deliberate slowing down of these within the terms of the contract. I think the most recently published completion date for both is September 2026, well behind what was being said 1.5 - 2 years ago.