Assuming you mean that the front derailleur can't even get far enough if you force it by hand, and also assuming you've got the original cranks: FC-2450 gets to its correct 43.5mm chainline with a 113mm Octalink V2 spindle. Shimano's listed BB for them is BB-ES300 in 113, although any other 68x113 Octalink V2 would work. If you've got a 118 on there, that could be causing the problem - the chainline will be around 46mm, which no Shimano road groups use. You write that it has a 73x118 BB, which is curious - road bikes "never" have 73mm shells, or should. If that's indeed what you have, it sounds like something someone put in by accident.
Like the other long-armed Shimano front derailleurs, FD-4700 needs a lot of cable tension and also needs its "converter" set to the correct path (the little flippable thing by the cable anchor. Errors with either of those could result in the shifter not being able to move the FD out far enough, but you would still be able to force it over by hand.
Edit: I did some more research. This is indeed a rim-brake, 130mm-spaced road bike with a 73mm shell. That is truly an odd combination, basically an unequivocal mistake on the manufacturer's part, and it is going to present some challenges. I don't know what the maximum chainline the 4700-level Tiagra FDs can take are - Shimano simply lists 43.5 for the double and 45 for the triple. Since the limiting factor here is the chainline of the outer ring position and cranksets can vary a little in their ring-to-ring spacing, getting to a definitive answer in the abstract about what will work can be tricky when one is pushing the limit of an FD's reach.
If you're looking for a simple answer that doesn't have you buying a new crank, this is the first thing to do: measure the current chainline and the various potential interference spots that could arise if you were to move the crank in with a shorter spindle, like between the large ring and the chainstay. If you can make the chainline match the spec your new FD wants (43.5mm for FD-4700 or 45mm for FD-4703), it will probably just work. The probably is because the ring-to-ring gap being bigger than a 10-speed FD expects could theoretically throw it off, but it probably won't be enough to matter.
If the above didn't work with the crank you have, the remaining options all involve buying a new crank or changing the ring size, depending on what crank you have, which again we don't know.