We do the best we can and are always improving, obviosuly some people are moving to mojoPortal from Drupal even though Drupal has been around longer. So we must be doing some things right.
On the GD error you got at some strange linux host. mojoPortal has no direct dependency on GD and I have never ever encountered that error or had it reported before. Mono has a dependency on it for their implementation of ASP.NET, mojoPortal just depends on ASP.NET. I have no plans to test whether all the Mono dependencies are there, that is outside the scope of mojoPortal. Development is not free, not even open source development, I must stay focused on adding value. I will only be spinning my wheels and getting no where if I try to handle every possible thing that could happen under all configurations and environments.
Its a simple ASP.NET fact that if you force a particular culture to be used for resources, the resource files need to be complete for that culture. We set a label just using simple syntax btnSave.Text = Resources.ResourceFileName.ResourceKey
It would be crazy to wrap a try catch around every label assignment. The only correct solution if you want to force a particular culture is to make sure the resources for that culture are up to date, I cannot keep them update myself, it has to come from the community, I only speak English.
One of our consultants from Italy, Wlater Ferrari has begun work on a tool to help identify missing resource keys and makes it easy to fill in the missing ones. Once this is complete it may help in keeping the different translations up to date.
Though I see your point about French users with their browsers set to English, and understand why you want to force French, I cannot change that fact that missing keys are going to cause exceptions. In many cases it is usually better to go with the browser preferences. For example the mojoPortal Persian Community, mostly will have Persian speaking visitors but if an English speaker like me stumbles upon the site the labels adapting to my language help at least a little.
You've been trying mojoPortal on all different environments and dbs, sorry if it annoys you to find some errors in some configurations but nothing is perfect and I am striving only for excellence not perfection.