Those articles seem to overstate their case a tad. For example, here's a quote from one of the internal-use-only documents being bandied around as proof Exxon knew about the impacts of climate change:
"However, the quantitative effect is very speculative because the data base supporting it is weak. The CO2 balance between the atwosphere, the biosphere and the oceans is very ill-defined. Also, the overall effect ofi ncreasing atmospheric CO2 concentration on the world environment is not well understood, Finally, the relative effect of other impacts on the earth's climate, such as solar activity, volcanic action, etc. may be as great as that of CO2."
Sound familiar?
In any case, that doesn't seem to be what this lawsuit is about. If I'm understanding it correctly, Exxon used a higher proxy cost of carbon ($60/ton) in their externally-published justification for why their fossil fuel reserves are unlikely to become "stranded" (economically unviable to extract) due to carbon taxes than they used internally when deciding what would be most profitable to invest money in ($40/ton). The prosecutor alleges that by doing this, they mislead investors into thinking they were applying higher projected carbon costs than they were actually using.
Frankly, it doesn't sound like a very good case. The stranding analysis literally says "We do not publish the economic bases upon which we evaluate investments due to competitive considerations." In addition, higher carbon taxes can affect the profitability of future investments in both directions - making efficiency improvements and clean energy investment more profitable but ones that produce more carbon emissions less so - but only increases the risks of reserves being stranded, so it seems highly prudent to use a higher carbon tax figure than they're actually expecting when assessing the risk of stranding, especially given that it could entirely wipe out the value of their reserves.