With so many WCs to be handed out Maia should have known that she would have been in contention for WCs so I think it's a conscious decision not to play in England.
For Fran, while there may be more points (and money) on offer back home, with the sheer number of tournaments this week and next, fields are going to be spread so it makes some sense to make the step up to her first 25Ks now to get that experience. That said it is a bit of a strange choice to choose a surface you've never played on before as your first 25K. It may have made more sense to choose a clay tournament as that is the only surface she's played on since Junior Wimbledon last year.
The weather in Obidos has been generally pretty bad and again this past week and seemingly next week. But partly basing an entry strategy on GB weather vs Portugal weather I'm not sure of as a general strategy.
Both Maia and Fran are down for Obidos next week, then Maia is currently an alternate for the Ilkley 100K. Fran is down for the Uzbekistan 25K in Ilkley week.
I would think Maia is at least in contention for a Wimbledon Q WC, after our GB # 3 to 9 probably take up 7, unless they stop at 7 for the initial total GB MD plus Q WCs.