Since version 10.2.1. both Thyme Warp and Gold Leaf can be upgraded.
But no seeds for them can be obtain from Neon Mixtape Tour / Lost City Pinatas's.
I also was never able to get any by playing Adventure (via the 3 daily pinatas).
I've only 2 options when opening "Find more" on these plants = a pinata with 15 seeds for 15 gems with 60% chance to get seed for them.
You can also obtain more seed packets for gold leaf and time warp if you click on them in the plant/zombie encyclopedia (blue book icon in the top left corner). Every day there is a different plant family available for seed packet purchase. When their respective plant family is available for upgrades, which is less often than some others, you can usually buy five seed packets with coins, five seed packets with gems, and watch ads to get one seed packet for each ad. I’ve been doing this for over a year and I have them each around level four.
