Word for "Significant enough to make a difference"

Solution 1:

You should consider nontrivial which means something which is not trivial (and hence should not be ignored).

"We need to find results that are nontrivial."

ODO:

nontrivial
ADJECTIVE
1 Not trivial; significant.

‘In the second half of the eighteenth century, a significant share of rural households in southern England suffered non-trivial declines in real income.’

trivial
ADJECTIVE
1 Of little value or importance.

‘Very often qualitative studies seem to be full of apparently trivial details.’

Solution 2:

A result is said to be meaningful when it has some real-world significance.

full of meaning, significance, purpose, or value; purposeful; significant:

Dictionary.com

Solution 3:

In some legal and financial contexts, an option is material. That would mean an event/action/adjustment that is likely to affect some important outcome. For instance "A tax rate increase of 10% would make a material difference to our profitability."

Merriam-Webster:

... having real importance or great consequences

For the accounting term: https://en.wikipedia.org/wiki/Materiality_(auditing)