Can the nRF52832 support higher data rates:
any trick to get them working so?
No and No.
To make it longer: the only trick which seems to be possible is to go with TWIM->FREQUENCY and UARTE->BAUDRATE registers outside of their spec. The values are not "locked" in the controller (at least according to specification here and here) however it's very unlikely that they would be stable so much out of tested and design range. Even if you get lucky on one of 5/10/100 chips to get it significantly higher then 400kHz/1MHz you won't be able to keep this across large batch of chips. There were similar questions on this forum, see what Nordic team says...
The 1 MHz I²C hardware uses faster transmitters with current souces. These are not present in NRF5x chips.
For UART, see: this answer here