It’s at, not on. Negotiations at the European level. Coronavirus cases still at a high level. Figures at the level of the individual business units.
There are two things to get right here, in fact. Not only do you need to use at rather than on, but there is also always an article (the or an) that Dutch sometimes dispenses with (op Europees niveau). So it’s:
- Negotiations at the European level
- Coronavirus cases still at a high level
- Figures at the level of the individual business units
The idiomatic phrase on the level, by the way, means ‘honest’ – without deception, truthful.
(And there are other constructions too, such as “aiming for a high level“, but the the Dutch there isn’t generally op.)
Prevalence: very high. A mistake that more Dutch writers will probably make than will get it right.
Frequency: high. Turns up in all kinds of contexts.
Native: no. It would be a good sign someone’s gone a bit Dutch.