There is time to successfully address these problems. Hopefully it can be done by some rethinking of the footprint of the overall project. But, if not, there are multiple ways adjustments which can be made to make the area more pedestrian friendly, some of which are addressed in the above article.
Additional uses might also be added to that stretch of Pico to attract people to the area at times neither the stadium nor the Pico Hall are being used. And by making those uses places that would attract people entering and exiting the two big venues, that could also make it more likely some people would arrive earlier and leave later, easing traffic congestion.
Another possible partial solution is to make the part of Pico covered by the new convention center into something resembling a very LA version of the Fremont Experience in Las Vegas. One that would be far more subtle - and which would be one continuous non-stop experience - paced so that the slow - and very gradual - changes in the lights would be observable by pedestrians, but not noticeable by the drivers along Pico so as not to distract them.
One or more of these shows might even be done by one of LA's 'light and space'' artists such as James Turrell. or Robert Irwin. This could give the area a major new cultural attraction and considerably ... brighten... the experience of walking along Pico.