The holes are called "VIAS" and they do interconnect the tops and bottoms AND the middles (if you have multi-layer boards) If you have a connector where the pins pass all the way through the board and out the other side, then the pins will carry the load to the opposite side - but you have to use a lot of solder to fill up around the pins to get from the one side to the other and let it all heat up or you will not make a good connection. From what I see, the pad under the "I" of INPUT looks pretty bad. I don't envy the work ahead of you. You could use direct jumpers but I assume you have a connector that is supposed to go here?
For what it is worth, I have done this kind of work for over 30+ years.