Riga - Tallinn by train: is this 4-minute change realistic?

I'm looking into travelling from Riga to Tallinn by train. From the invaluable Seat 61, I know that this involves a cross-platform change at the border station of Valga, arriving 13:55 and departing 13:59. A four-minute change is no problem if the first train is on time, but potentially a major problem if it isn't.

Under the circumstances it seems reasonable to expect that the Valga - Tallinn service would wait for a slightly delayed Riga - Valga arrival. However, reasonable expectations aren't always met, so does anyone know whether this is likely to happen in practice?

(I know that it's faster, and often cheaper, to take the bus between Riga and Tallinn, but I am specifically interested in going by train and too impatient to wait for Rail Baltica :).)