This is a known Needle/Three.js behavior, not a Unity bug. The FAQ covers it directly:
For directional lights the position of the light is currently important since the shadow camera will be placed where the light is located in the scene.
— Questions and Answers (FAQ) 💡 | docs
In Unity, a directional light is infinite, so its position doesn’t affect shadows. In Needle Engine (Three.js), the shadow camera is placed at the light’s position, so it only covers a limited frustum — exactly your symptom: objects near the light’s location cast shadows (trees, bench, part of the curb), while objects further away (lamppost, house, other benches) fall outside the shadow frustum.
Next step: In the Unity scene, move the directional light so its position is centered over the area you want shadows, and/or increase the shadow distance/orthographic size (via the Additional Light Data component on the light, or the shadow camera settings). Re-export and the missing shadows should appear.
If you want to verify quickly, open the exported scene and check the light’s position/orientation in the browser inspector.
For project-specific help, ask Needle Cloud AI.