ᐅ Are additional costs too high or too low?

Could someone please give us a realistic assessment? Thank you!

This is about the "other" additional costs – are they too high or too low / is something missing?

For your information: No work will be done by ourselves, so we always need a company to handle it:

Outdoor areas (paths, terrace, garden, fencing) 9000

Construction electricity 1000

Construction water 750

Possible site-specific work due to groundwater, poor soil bearing capacity, etc.
9000

Wallpapering and painting 6000

Floor coverings 145 sqm (1560 sq ft), carpet upstairs, laminate downstairs ???? (Price not yet calculated, does anyone have an idea?)

Kitchen 10000

Garage including foundation 11000

All prices are approximate, of course 
The fittings should not be cheap, but also not high-end luxury.

I assume you are not referring to the ancillary building costs?
In that case, I have found the following items (I’m actually working on summarizing everything for the bank today):
Rainwater/drainage... 4000
Chimney sweep/drainage inspections... 500
but these are only estimates.
Then:
possibly satellite system + installation
exterior lighting

For carpet/parquet/laminate flooring, I noted down €50 per sqm (5 sq ft) for materials (I hope that includes baseboards, nails, and adhesive). We plan to do the installation ourselves; I’m not sure what a contractor would charge.

No one can answer your question because no one is familiar with your plot of land.
Fencing... how many meters (feet)? Terrace, what material? How large? With €9000 (about $9700) for everything outside, you won’t get very far. Especially since essential items are probably still missing 🙂
We are paying almost €6000 (about $6500) for a staircase, paving 90 sqm (about 970 sq ft), setting some curbstones, splash protection around the house, and leveling the garden a bit. And that is already one of the cheaper offers.
But that doesn’t include a fence, lawn, garden shed, garden path, etc. Just the bare essentials 🙂

For construction electricity €1000 (about $1075), do you mean consumption, or the rental and connection of the meter box?
Construction water cost us €10 (about $11) 🙂

Wallpaper and painting for the entire house will be interesting—whether you can find a contractor for that budget.
Are you laying the flooring yourself or having it installed?

For a kitchen, €10,000 (about $10,750) can be challenging depending on requirements. Our kitchen is quite simple for our standards. It was offered to us at prices between €32,000 and €19,000 (about $34,400 to $20,350). In the end, we paid €11,000 (about $11,800), which was only possible through our home builder’s cooperation with a specific kitchen studio. (Appliance prices found online were around €7500 (about $8000))

Hmm. The prices seem very, very low to me. We are paying about 2000 EUR for construction electricity. Kitchen 21,000 EUR, etc.

Our construction contractor is covering the temporary power supply; the box costs around 400?

For 10,600 euros, we got a NoXte wood lacquer kitchen... including a cooking island, about 8 meters (26 feet) of cabinets (with good interior fittings) in total, appliances from NeXf and AXG, a steam oven included, extra-thin countertop, and lighting. What I mean to say is: 10,000 is well estimated, unless you specifically want a built-in wok, grill, or all those other extras 🙂