Pretty hard to diagnose an issue like that at a distance, and with no details at all, but here's a checklist:
Is inner chainring on backwards? Sometimes people would flip these and the inner spacers would fit into the recesses meant for the chainring bolts, throwing off the spacing.
Front derailleur height? I recommend using the standard height from big chainring. "penny thick". Never had it not work. Check the basics.
https://www.parktool.com/blog/repair...eur-adjustment
FD alignment? Generally outer cage should be parallel. Older FD will benefit from tweaking, and imperceptibly small inward cant. Can't explain that by text.
Chain length? IME the jockey cage vertical in biggest gear (shimano method) works better than the big/BIG +2 method for triples. Wrong chain length can really mess things up.
Try a different chain? Old stiff chain may be problem.
Lastly I'm guessing he's using vintage FD? As mentioned above, modern 'triple' FD are designed for specific chainring sizes and tooth counts, and are not flexible. Vintage FD work better for vintage style triples. CX-70 is a good modern derailleur for road triple.