Hello!
When Apple replaces the battery, it should fix the trackpad issue. If not, Apple can service that for you as well!
You can start your Apple repair here: Get Support.
As a reminder, only go to Apple, an Apple Authorized Service Provider, or send your device to Apple for service (if applicable or available). Do not go to a 3rd party/unauthorized repair center or attempt a repair yourself. This is for the assurance of authorized and professional repairs that use genuine Apple parts. Please refer to this from Apple Support:
Beware of counterfeit parts
Some counterfeit and third party power adapters and batteries may not be designed properly and could result in safety issues. To ensure you receive a genuine Apple battery during a battery replacement, we recommend visiting an Apple Store or Apple Authorized Service Provider. If you need a replacement adapter to charge your Apple device, we recommend getting an Apple power adapter.
Also non-genuine replacement displays may have compromised visual quality and may fail to work correctly. Apple-certified screen repairs are performed by trusted experts who use genuine Apple parts.
Jack