Hello,
This may be data related, but also I see that there is some logic on this API to calculate amounts. But for me at least the data is different. First I run it without a date filter:
https://api.businesscentral.dynamics.com/v2.0/12345a290c-abcde-4e49-afcb-daf662adc134/Production/api/v1.0/companies(0f8058e0-affd-ea11-bb48-000d3a2fece2)/trialBalance?$orderby number

For account 10200, BalanceAtDateCredit is 428,888.90.
Then I apply the filter:
https://api.businesscentral.dynamics.com/v2.0/12345a290c-abcde-4e49-afcb-daf662adc134/Production/api/v1.0/companies(0f8058e0-affd-ea11-bb48-000d3a2fece2)/trialBalance?$orderby number&$filter=dateFilter ge 2019-01-01 and dateFilter le 2019-12-31

Now the balance is 313,421.50
So the filter has an effect at least. I guess only for the "balanceAtDate"-fields. At least that's how it looks on my setup. I don't know if that helps you - of course it does not help you that it works for me if it doesnt work for you?