[D&D 5e OGL by Roll20] Miscount Spell Point for paladin, ranger, artificer from level 5

Upon reaching level 5, these classes each have 6 spell points when they should have 14. When calculating the number of spell points, takes the number of spell slots of the previous level

Paladins and Rangers are correct. To calculate their spell points you divide their level by 2, round down, and then consult the table.  Artificer have no official rules for spell points. But, based on the spell slots Artificers get they should be divide by 2 round up. Ie: one level higher than is currently shown.  I suggest doing Artificer spell points manually. 

If you look like this, then everything works correctly. But I interpreted this rule as transferring spell slots to spell points using  Spell Slots per Spell Level  Tables  and Spell Slot Cost. Thus, these classes will have the same functionality as when using spell slots. For example, at level 5, using cells, you can cast 6 spells (four 1st and two 2nd), and when using points, either three 1st or two 2nd. This greatly reduces the ability to use spells in the game.

Looking at it again, I see you are right, 5th level 1/2 casters do not have enough spell points to cast all of their spell slots.  However, the problem is not with Roll20, it is with the DMG.  "For a paladin or ranger, halve the character's level in that class and then consult the table." (DMG p288) By rule, all fractions are rounded down unless specified otherwise. Since they didn't specify it, that is the problem. Roll20 is technically correct, even though we all know in this case it should be rounded up to give the proper number of spell points.