"a great contribution" is correct and usable in written English. You can use it to reference any kind of contribution, such as physical assistance, money, or a service. For example, "John's involvement in the community is a great contribution to the betterment of the neighborhood.".
"I've made a great contribution.
"They do make a great contribution.
Dyslexic people make a great contribution to our society.
Either way, the study is a great contribution".
"I think it could be a great contribution.
Chad Griffin, an activist against Proposition 8, said Mehlman had made a great contribution.
"They really made a great contribution to what was known about Antarctica," said Simonsson.
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.
Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com