Hello,
Thank you for reaching out!
This really depends on what you prefer - if you want to achieve maximum performance, then both of the antennas should be pointed to the same tower. If you prefer stability - point each of them to a different tower.
If the towers are generally in a similar direction, I'd just point the antennas to one of them, as even the best directional antennas will reach the towers they are not pointed to (but the signal will be weaker).
As for causing any issues - it will not. The router will connect to one tower anyways, so it should be all good, with the exception of a little poorer performance if the antennas will be pointing to different towers.
Best regards,
DaumantasG