有关资格证明文件的翻译

此证明指有关机构出具的相关资格或技术技能证书，
This certificate concerns relevant qualification or skill certification given by related units.

如无此证书，应由该外国人原工作过的单位出具从事现聘用岗位工作相关的资历证明，或提供相关的学历证明。
Without this certificate, proof of working experience related to present employment or relevant education background from the previous unit the foreigner ever served should be provided.

机构 -> entity/organization

此证明指有关机构出具的相关资格或技术技能证书，
The certificate refers to the related qualifications or the technical skill certificate issued by the related organization.

如无此证书，应由该外国人原工作过的单位出具从事现聘用岗位工作相关的资历证明，
If you does not have this certificate, a correlation qualifications and records of service proof should be given by the original work unit, to prove the foreigner has been engaging in the presently employment.

或提供相关的学历证明。
Otherwise, you should provides the relevant education background .

三个分句， 应该清楚了。