Short answer: Yes, makhana (fox nuts/lotus seeds) is generally considered allowed in Jain dietary practice, but there are caveats.

• For regular practice, makhana is a seed, not a root, so it is ordinarily bhakshya (permissible) for both Śvetāmbara and Digambara Jains. ( jainknowledge.com)
• During Paryushan or other stricter vows, many Jains avoid foods grown in water or that may involve higher himsa (harm to tiny life-forms). In those periods, makhana is often avoided, depending on local maryada and guru guidance. ( jainknowledge.com)

If you want, you can read more about how different practices view makhana here: