Even if we can't _fix_ all those systems, getting reliable predictive/status markers would be a good start. Just being able to scan for ten or twenty blood markers and work out which aspect/s of health someone needs to focus their efforts on improving. It doesn't feel like we're a million miles from being able to do that now.
As to the multiple systems - we probably want to add hormonal and short/medium term regulatory systems to that list (being able to activate even a 40yr old's motivational/dopamine response in a 75yr old would be a significant step). And take into account that there are designed-in trade-offs (slower cellular repair in ageing bodies is very possibly an evolutionary adaptation to deal with higher cancer risk in cells with more mutation damage, for example).