I brought food back and forth through both US customs and Australian customs for yonks.
What I did was pack it in one easily accessible place, write out a complete list, declare it, and present the list with the arrival cards/passport.
Even if it's not a legal import, as long as you declare it you are covered. They can throw it if it's not legal but they don't fine passengers who genuinely try to do the right thing.
Nothing I brought and declared was ever thrown out - even the ghastly cheese-in-a-tube from the USA which had about 6 officers humming and scratching their heads over - they quite rightly decided that it was more like plastic than cheese.
Your Golden Syrup will be fine, but the plastic containers will present less problems than the metal container.