I really appreciate your feedback, thank you! I have edited it to read:
If you choose to gain a wig from the Trade Zone, adjust the foraging value for the next wig to “+8 for the rest of the Season”.
Hopefully this makes it clearer, although your comment about it fitting with the rest of the Meltwater events is also a very good point. It is definitely something of a flaw in this little fan-made expansion, and something I will think about further - whether that's to remove the mechanic adjustment completely or something else. I shall upload the current edit next week as I'm currently on holiday, but thanks again for your feedback!