The cabin is visible (wood tones), dock visible, but the "pond center" sample shows dirt color (0.42,0.37,0.30) — that's the ground/path color, not water. The pond might be barely visible or the water is below the ground. The pond far edge is off-screen. The pond is positioned mostly below the frame.

Also the "pond_center" at ndc (0.67, 0.18) shows PathMat color — that suggests the pond water surface is not being rendered there, possibly because the ground mesh covers it or the water is hidden.

Let me check the pond water position vs the ground. The pond center (8,-7) has terrain height -1.19, and the water disc is at z=0.25, radius 7. The ground mesh around the pond dips to -1.19 at center, and the water disc at z=0.25 covers it. But the sample at (8,-7,0) shows dirt — maybe the camera ray hits the water but the water is transparent and shows the ground beneath (transmission), or the water disc is small relative to the pond depression.

Let me verify the pond water is actually at the right place and visible.

import bpy, math
from mathutils import Vector
from bpy_extras.object_utils import world_to_camera_view

mc = bpy.context.scene.collection
pond = bpy.data.objects['PondWater']
print('pond loc', pond.location, 'dims', pond.dimensions, 'verts', len(pond.data.vertices))

# check terrain at pond edges
def th(x, y):
    h = 0.35 + 0.14*math.sin(x*0.45+1.1)*math.sin(y*0.4-0.6) \
        + 0.08*math.sin(x*1.1+3.0)*math.cos(y*0.9+1.5) \
        + 0.05*math.sin(x*2.3+0.4)*math.sin(y*2.1+0.9)
    dc = math.hypot(x+4, y-1)
    if dc < 7.0:
        t = dc/7.0; s = t*t*(3-2*t)
        h = h*s + 0.55*(1-s)
    dp = math.hypot(x-8, y+7)
    R = 6.4
    if dp < R:
        t = dp/R
        h -= 1.5*(1-t*t)*(1-t*t)
    return h

for x, y in [(8,-7),(8,-0.6),(8,-13.4),(1.6,-7),(14.4,-7),(4.6,-4.9),(7.2,-6.2)]:
    print((x,y), 'terrain', round(th(x,y),3))

# camera view of pond center point at water surface z=0.25
cam = bpy.data.objects['Camera']
scene = bpy.context.scene
v = world_to_camera_view(scene, cam, Vector((8,-7,0.25)))
print('pond center surface ndc', (round(v.x,3), round(v.y,3)))