Changing radiators to radiant wall heating
Changing the delivery method in the room does not address the (evident) actual problem of having the space controlled by a thermostat in a different room which does not track well with it.

Radiant wall can be a nice setup, but it is also very slow to respond, so you will probably make the disconnect between the living room thermostat and the bedroom worse, not better.

Unless you have a major desire to try radiant wall, simply splitting the heating into more circuits (a bit more pipe, and valves or pumps, and another thermostat) will solve the problem you describe reliably and with less disruption to the house, and for less cost, by isolating the bedroom heat to a circuit controlled by a thermostat in the bedroom.

If you do have a desire to try radiant wall, you will still want to separate the heating loops, and the radiant wall loop should probably also have a control to reduce the temperature in that loop (it's a common item - "injection circulator" is one term, there are also valves to achieve the same end) basically the fluid in the wall is running around a loop that is connected to the loop from the heat source, but only enough hot fluid from the heat source is added to the loop to maintain the lower temperature suitable for the radiant loop, rather than running the full flow of high-temperature fluid through the radiant loop.