That looks bad.
The leaves are dehydrated. Check the moisture in the soil using your finger. Don't use a moisture meter or other gadget, just stick your finger in the "dirt" at least as deep as the distal joint. Stick your finger in several different spots.
Wilted leaves means the roots are not moving water into the tree. This can happen when the soil is too dry, or when the roots have been damaged.
If the soil feels dry, either everywhere or in spots. Then your tree needs water. The way you need to water is to bring a sink, flood the pot with water, then allow to drain a few minutes, then flood the pot again, allow to drain, then return to the windowsill or the grow light set up.
If the soil feels moist, this means the root system is not functioning, usually a sign that a rot has destroyed the root system. This situation, when root system is no longer functioning, to the degree of wilt in your photo is usually fatal.
Often this situation comes from alternating between too dry followed by prolonged wet soil.
The trick with watering bonsai is to allow the soil to dry to "just barely moist", but not so dry that the leaves wilt. Then water, then allow the tree to approach dryness. If allowed to get too dry, the dry soil will damage the fine roots that absorb most of the moisture. Watering is best done by walking the tree to a sink, flooding the pots with water, allow drain, do it a second time just to be certain there are no "dry pockets" in the pot. Let drain, then return to the windowsill or lights set up.