The résumé of somebody's life provides a good opportunity to look at the progression of verb tenses from the starting-point up to the present day. It's important that
the simple past tense can used for everything until the first connection with the present appears. So: gained, went on, worked, was, remained, became.
It is not important how far the résumé goes back into the past - the simple past is good for everything which is related in the same order as it really happened, i.e.
chronologically. The past perfect (had been, had worked, had become) is only needed when the chronological order is mixed up, producing flashbacks suggesting "ešte predtým" in Slovak, e.g.: "When
USS took over the Košice steelworks in 2000, he had already been IT manager at Transtar for five years". This makes the style of the résumé rather more literary.
When there's a link with the present, the tense changes to present perfect ("For the past year he has been..."), and it's neat to finish with a present tense ("Both...
live..."), bringing us fully up to date.